And to expand on that that, I think more closeted horniness, is really where most of this comes from. I think the "X haters keep getting caught watching X porn" stuff is more a symptom that happens later on down the line.
Part of this is just because we live in a society with a thousand different views of sex, not a single one of them healthy and don't really a great way of talking about sex for as much as we talk about it.
What you want in a sexual partner is hard to explain for a lot of people, and not just people from non-traditional sexualities.
I think people, young men especially, get talked into or talk themselves into the idea that unless they are 6 foot 4 and drive a Bugatti they are going to die alone and yes this is getting close to the whole "incel" thing a can of worms I can't imagine will improve this discussion all that much so I'm going to keep this in the vague and broad strokes but I can... get, not endorse, not even understand, but "get" on a very basic level the fear of having your potential partner pool reduced, even symbolically.