Actually, it's pretty fundamental to Game. Perhaps one of the most important aspects. But let's start with the initial question of whether or not you should initiate or wait for her to initiate.
It's interesting, once you get this down, just who is "initiating" becomes cloudy.
Athol's point about female sexuality being responsive to male sexuality is dead on, and that's a foundation of Game Theory. Especially within a marriage or
LTR, once you understand this point instinctively you become far more aware of the subtleties leading up to actual initiation. And once you do understand it, and your wife begins reacting to you more regularly, then patterns evolve in which SHE will let you know that she's interested in you initiating sex through some small symbolic gesture, phrase or mannerism. It might be as mild as a playful dig or discussing someone at work's sex life, but if you carefully observe her behavior then you'll start to pick up on these cues.
That's one thing that the feminist revolution really messed up. In promoting the idea that women could initiate a sexual relationship and have sex without it having been initiated by men, it spread the erroneous idea to men at the time that since these fully-empowered, sexually active women could initiate sex without being condemned for it, that they would naturally start initiating sex roughly half the time.
That took a lot of pressure off of dudes, because the less they initiate, the less they get rejected. But after the novelty of early sexual exploration wore off and young couples had to face the intricacies of a day-to-day sexual relationship in a long term relationship, men continued to expect the more aggressive sexuality of their woman's single years, i.e. she initiates sex about half of the time, whereas their women usually lapsed back into the monogamous pattern of waiting for their men to initiate, as Nature programmed in us. And when the menfolk just didn't, because they took the feminists at face value and backed off dominant tactics, frustration and anxiety set in on both sides.
The problem is that feminism has put such a stigma on male sexuality that women are brought up to both desire male sexual attention and fear it. That sucks for them. And we dudes were brought up being taught that aggressive sexuality -- which included attempting to initiate sex -- was inherently disrespectful of women, and that the proper thing for a good little boy to do was kiss your woman's ass until she decided she was ready to have sex with you (the Betaization), because to manfully initiate sex like your forefathers was an affront to the inherent spirit of independence and person-hood of women as human beings, and yadda yadda yadda after that we just kind of stopped listening. We got the message.
Oh boy, did we get the message.
Between the fear of divorce, sexual harassment suits, and diversity training classes, the men of Generation X were taught to fear and respect female sexuality. They were also taught that women could initiate sex and not be considered sluts. In fact, they were pretty much instructed exactly what hoops had to be jumped through in order to have a pristine, politically-correct sexual experience complete with two condoms and a signed indemnification form. For all practical purposes, we were taught that Nice Boys didn't initiate sex . . . they stood there and waited for it to happen by the grace of womanhood alone.
Big problem with that, though. Sex doesn't work that way. Because it's pretty clearly understood that women are designed to be sexually reactive, and men are designed to be sexually proactive. Even Emily Nagoski the Sex Nerd, noted feminist scholar of human sexuality, is perfectly willing to admit this. She pretties it up by demanding that women tend to have "responsive desire", while men tend to have "spontaneous desire", but it comes down to the same thing: men are proactive about sex, women are reactive. If a man doesn't act, the woman can't react. She hedges her bets by pointing out the usual NAWALT argument that spontaneous and responsive desires are not gender-dependent and vary greatly from individual to individual -- all perfectly true -- but as my old physics teacher always said, "the race is not always to the swift, nor the battle to the strong . . . but that's the way to bet." So if you want to qualify the statement, you can always get away with "Men, in aggregate, tend to manifest Spontaneous Desire more often and more easily, while women, in aggregate, tend to manifest Responsive Desire more often and more easily."
In other words, "In general, women don't start getting hot and thinking about having sex until a man comes along and gives them a reason to." That doesn't mean that she won't have lusty, nasty thoughts at any given hour of the day . . . but in terms of acting upon those thoughts, it's less likely even in this egalitarian day-and-age that she will initiate sex of her own accord without first being approached by a man.
An ironic point about Emily's post is that she pitches this idea as a feminist demand for acknowledgement that women are different and special creatures by pointing out that she's tired of sex researchers using the language and standards of male sexuality to evaluate and judge female sexuality. And while her point is well-taken -- male and female sexualities appear to be very different in make-up and mechanism, and sex researchers have traditionally been male and used male paradigms for evaluating female sexuality -- it also undermines the feminist approach to sex in which male and female are theoretically equal in all important ways (which leads to the pragmatic result of women becoming more dominant in their personal relationships by default, as men ceded the initiative under the blistering attack of feminism on their masculinity).
It's a feminist axiom that men and women ideally enter into a marriage or relationship as an "equal" partnership. In the feminist marriage, there is no implied obligation or expectation of sex on either party's part -- under feminism, sex cannot be institutionalized in any way without damaging the independence of women as individuals. If it happens, it is by the grace of the woman to bestow it, regardless of the man's behavior, and she alone controls access to it by custom, if not by law. Any less than enthusiastic and willful participation by the woman is tantamount to a non-consensual tryst, goes the theory. In some extremes, she can even change her mind about her consent after the fact, and let the hamsters fall where they may.
But all of that lovely ideology falls apart when the rubber hits the well-traveled road. If biology demonstrates that women tend to have "Responsive Desire" -- and that is held up as a proud difference between male and female sexualities by one of the noted feminist researchers -- then it's really very difficult to argue any pretense that the goal of "equality" in a sexual relationship, especially in a marriage, is contrary to our biology.
That may make little difference to the "gender is a social illusion" crowd, who push to have gender concepts in general stripped away from our culture in the interest of fairness. But for the rest of us, the ones who are actually going out and trying to get laid, this is a vital and fundamental fact that cannot be ignored by pretending it would be better if we all just acted like it didn't matter to anyone if we were boys or girls. Because when you do that . . . well, you stop getting laid. Androgyny occasionally slips into our culture as a novelty, but when it comes down to it we persist in recognizing the pretty clearly-established fact that there are bigger differences between men and women than our choice of position when we urinate.
Just take a look at the phenomenon of "Lesbian Bed Death". It's a truism that lesbian couples in long-term relationships often just . . . stop having sex, even if they were fairly lustful at the beginning of the relationship. The "Reactive Desire" idea, applied in this sense, demonstrates that if two people who are both "reactive" are in a relationship, you get a lot of "so do you want to have sex tonight?" "I dunno, do you want to have sex tonight?" "I dunno, it depends on whether or not you want to have sex tonight?" "I could have sex, but it's totally up to you." "Hey, isn't there a This Old House marathon on tonight?"
Similarly, gay men in relationships tend to have a lot more sex than straight people or lesbians, especially in the heady days of their early 20s when testosterone turns every male into a horny slab of testosterone-poisoned sex-zombie willing to bang anything that doesn't run away fast enough. When both partners enjoy "spontaneous desire", you can bet that there's a whole lot more DNA flying around.
So the science says women are reactive, men are proactive. Feminism says to ignore that and focus on human rights issues and universal deference and respect for vaginas, letting them do as they will of their own accord. After ignoring the custom that supported the science for three decades, and suffering a societal retrenchment of mating customs the likes of which human history has never seen before, eventually the damage got bad enough so that a couple of dudes said "hey, all that stuff about us waiting until the woman says she's ready for sex on her own? It's really all kinda bullshit!".
And then they went and developed Game, because they realized that if they, as men, didn't take responsibility for attempting to initiate sex 100% of the time, then they got a lot less sex. When you wait around patiently for the one in the relationship with "responsive desire" to suddenly generate interest in "spontaneous desire", then you're going to be waiting a lot. And then your woman will quit being attracted to you and start to cultivate other options. Welcome to Blue Pill Betahood, where they put the 'blue' into 'blue balls'!
Indeed, for most dudes in the Manosphere you can trace back their realization that they just took the Red Pill when they realize that the same sexuality that has been castigated and demeaned all his life is evolutionarily designed for him to try to initiate sex all the damn time as an inherent expression of his masculinity -- it's not a sign of a character flaw or a medically treatable condition. Dudes are horny, they try to have sex with girls, and that has nothing to do with their deeper political beliefs about the role of women and gender in our society. And once they realize that -- and accept that if they want sex, they and they alone are responsible for initiating and managing their sexual relationship -- then they can relax, safely ignore all of that crap about the politically correct method of coitus, and get his freak on like Nature intended by initiating sex without fear of judgement.
And yes, he might get judged . . . but the next step on the Red Pill journey is ceasing to give women the power of judgement over you. Yes, once you realize that to screw them you have to ignore what they say and pay attention to what they do, then what they say even about you gets a lot less credibility. Case in point: college girl I knew absolutely hated the whole macho Alpha image thing with a passion, to the point where she would confront jocks and d-bags in the college cafeteria about their alleged douchebaggery and lack of respect for women by these oversexed walking phalluses . . . and then at the end of the semester she was the FB of three dudes on the wrestling team who could care less what she thought about them. It wasn't her opinion that they were trying to get into.
So the best thing a dude can do is suck it up. Accept the fact that despite what our popular culture might be saying, in fact the female sex drive tends to be reactive, not proactive, and that you will have to put forth more effort than you'd probably like if you want to improve your sex life. Deal with it. Because if you wait for your reactive-desire wife or girlfriend to suddenly develop spontaneous desire, you're going to be there for a while. With blue balls. You have to step up and aggressively pursue a consistent strategy of seduction and pursuit or you're locked in Blue Pill Betahood until the divorce.
It's possible to be sexually proactive and not be a douchebag. Indeed, a lot of happily married couples with long histories figure out ways to do just that, and end up enjoying a long and lusty sex life. The ideal Red Pill goal is to get to a place where your ability to initiate gets distilled down to a comfortable, easy-to-recognize signal that immediately dampens panties.
That's the beauty of Married Game, and the difference between it and Dating Game. In Dating Game, the goal is to establish a relationship that leads to sex with the least amount of effort and expenditure of resources as possible. Married Game's goal is to establish a pattern of sexual behavior in a relationship that encourages an interpersonal intimacy in which sex is not "if" but "when", with the least amount of effort and expenditure of resources as possible. In Dating Game you're hunting wild pussy. In Married Game, you have domesticated pussy available. But if you don't husband it properly by consistently and aggressively initiating sex with your woman (paying particular attention to her menstrual cycle) and giving her the opportunity to react favorably, then no matter how well the initial domestication went, you're going to have problems on your hands and more porn on your computer.
It can be hard. Once you take the Red Pill, and understand the realities of the situation instead of focusing on some theoretical ideal of sexual equality your relationship is supposed to measure up to, then you can accept the idea that initiating sex is your responsibility as a man, not your (plural) responsibility as a couple. If her sexuality is reactive, and you aren't being proactive, then she's going to sit there in neutral and start doubting her own attractiveness, and therefore the strength of your relationship, and that way lies madness.
So suck it up. Forget about how nice it would be if she just came in, dropped her panties, bent over and said "do me, please". Because the fact is, if you want to cultivate that kind of response the only way it can be done (without recourse to pharmaceuticals of dubious legality) is by cultivating a proactive pattern of sexual behavior in which you do initiate often and enthusiastically enough that she feels confident and secure enough to initiate sex herself without fear of rejection (which women handle and interpret entirely differently than we do) secure in the knowledge that yes, you do find her irresistibly attractive because why else would you be trying relentlessly to nail her all the time?
So suck it up and go make out with your wife. If you do it right, she'll forget all about who started it.