I agree that there are probably many different roads leading to these same fetish communities. And as I've mentioned before, communities thrive on the momentum of simply being a group, so after a while the subject and source no longer matter, as they pale in comparison to the rush of belonging to a team. However, I think one of the paths that lead to shit like this is a generation's inability view the world without the lens of pop culture.
In America, we have this really weird idea about not just sex, but who is allowed to even know it exists. If a school tries to teach sex education, you get tons of parents crying out that it's "warping the children," even if their kids are 16 and are dealing with sexual feelings. If they try to give out free birth control to teens, it's "condoning sin". Hell, if they try to teach them about their own bodies, they're accused of befouling innocent minds. Parents who yell about this swear that they want to be the ones to teach their own kids about this stuff, but of course they don't actually do it. They instead tell their kids to just not think about it, to not ask about it, and certainly to not look it up. The mere concept of sex is simply forbidden knowledge. It's all under the pretense that if you don't even know about it, you'll save yourself for marriage like God commands.
But the thing is, sex sells, so we use it in advertising and entertainment. A LOT. Yet we can't go too far, lest a "wardrobe malfunction" permanently damage everyone's psyche. So we have to get really ridiculously coy about shit. Sitcoms don't get too overt, but rather talk about "who slept with who." Male characters in movies keep talking about "getting some," but we don't often get more information than that. A girl can have sex in a movie, but if she enjoys it too much, it can affect the film's rating because it's "too explicit." Am I saying I want to see explicit acts and tons of detail in a primetime comedy show? Of course not. My point is that nobody's allowed to learn about the realities of sex, and therefore their only teachers are pop culture, which in turn treats sex as a cartoonish mystery.
We like to assume that kids are just robots with blank memories, but they're not actually that stupid. They notice that "sex is a thing people really want!" is a widely popular recurring theme in every song and movie they consume. But since it's been treated as a forbidden mystery their whole lives, they can only process it as it appears in entertainment. It's an unseen macguffin. A running gag. A dramatic plot device that affects the rest of the story. So naturally, they get the joke. The male character on TV doesn't want to go to a museum, but the super hot female love interest leans over and says "pleeeaaase?", and suddenly, he instantly agrees to go! Haha, get it? He wants that Mystery Thing everyone wants!
But that's just it, isn't it? In these stories, you could basically replace sex with utter gibberish and it'd mean the same thing to these kids. Ha ha, the guy bought 30 extra books at the book store because the sales clerk was cute! Because he wants the flibble-flop-jimpy-jorps! I get it! Man, it feels great to be part of this group of people who get that joke, ha ha ha!
No, I'm not saying they don't literally know what sexual intercourse is. Most of them know about Insert Figure A Into Slot B. But they really don't know about anything that surrounds it. Sex is just kind of a phantom character that everyone talks about but nobody sees, so many of these nerds just treat it as such. I'm certain that for many of them, there's a horrendous problem of misplaced sexual desire. They get aroused, but they don't have any idea who or what to focus on, so they get attached to stimuli that's tangentially related to what they would have actually wanted, had they known what sex really was all about. You like caring for people? Well ok, but clearly it can't be about Actual Sex, since Actual Sex is a weird mystery thing that you can't really conceptualize... ah! Here we go! Sneezing! You like sneezing! You specifically are attracted to just sneezing and the sound of it and people being under the weather! and... that's it! Nothing beyond it! Juuuust the sneezing!
Think back to the mud fetishists, or the inflationists. Or the flat fetishists. Or the glasses fetishists. Rarely does sex even enter the equation. In many cases it seems as if it'd actually lessen the experience for the fetishists. Because at that point, your brain would have to confront the reality of Actual Sex With Another Real Human Being, and if you're like these people, your mind would draw a total blank.
It seems this problem could also explain huge subsets of the AVEN/Tumblr asexual community. The realities of sex are just one big question mark, so clearly pop culture will guide them! I mean my god, we've got people who honest-to-christ think that "I only want to fuck people I like" is not only so unusual that it needs its own label, but that it's an oppressed minority akin to the gay community. We've got self-described "aromantics" who describe their ideal nerd dates and then swear that such meetups would not be considered "romantic" because y'know, nobody's sharing a milkshake with two straws or writing overwrought love poems. There are folks out there that think the astronomically high number of sexual partners that sitcom characters have is the average for real people.
It's a huge issue that clearly needs to be addressed by our culture at large, but that'd mean tackling our Puritanical nature... and that's going to take quite a few generations. And by then we'll have mostly gone extinct anyway since we'll all be married to nonexistent waifus, so I guess it's a moot point anyway!
Also I fucking love this Asexual Bingo card and I encourage everyone to bulb it immediately, as I have.