Boy, there's a lot to reply to, so I'll try to structure a general response.
I am curious though, what do you think is heterosexual visual porn for women?
In this case, anything drawn/made to visually appeal to women sexually.
watch homos give each other GRIDS
Just to be clear, I am not including actual faggot-on-faggot action or other life-action porn. By 'gay porn' in my previous post I meant the BL comic genre. Most female nerds tend to use more stylised art for their shlickbait, and there are countless jokes about fujoshi freaking out when shown actual fags fucking. Speaking from personal experience, I have yet to meet a woman who honestly prefers irl porn to anything drawn/written.
Finding yourself in the position where all of your schlickbait is faggotry is the result of internet addiction and lack of real world socialization.
Those two reasons are too broad to really explain it, aren't they? You could say the same thing about furries, various kinds of loli-sho freaks, bizarre roleplayers, and other weird subcultures with large followings. Internet escapism opens the door to many degeneracies, but what exactly leads so many girls to this particular one?
A lot of mainstream romance novels have sex scenes in them very comparable to fanfiction in these categories. Many of them now are written by people who explicitly got started writing in fanfic. It's important to remember that a lot of women still prefer sexual content in works that have other story elements. It's still erotic and arousing but won't be found only in porn one-shots.
This brings us to the issue of M/F vs. M/M. Paper Machete is right in pointing out that femporn tends to be balanced with other elements like plot and character development, so more like a story with fucking rather than just fucking. This is true of both straight and gay romance stories. The real differences come in how exactly the sexual part is portrayed. This is where the visual part comes in. Men are simply not as openly sexualised on the het side as they are on the gay side. Or at least it was like that for a decade or so. While in some straight manga of the 2000s an artist would struggle to draw nipples for the guy, let alone a dick, a fujoshi artist would draw the men with all the juicy details and less censorship. The heterosexual sex is usually stale, sometimes even too metaphorically depicted with flowers and sparkles to understand what's going on. The BL, on the other hand, gives exactly what a horny girl wants to see, without forgetting the drama and character development. And let's not forget how the BL, thanks to the absence of women, can actually make riskier choices, touch on more controversial issues and use more violence - a perfect shock element that always attracts a bigger, more impressionable audience.
This is also a key element of why some rare heterosexual smut, such as Fifty Shades of Grey, has become so popular. Thanks to being a written form of entertainment and not actually showing anything to the viewer, heterosexual smut novels/fics are allowed to be more explicit in their content, but they are usually looked down upon or heavily criticised, while the gay ones more often get a pass. There's also this stigma that straight romance for girls is inferior or childish, which is also perpetuated by fujoshi culture. "A woman is always the self-insert, never the character, while the BL protagonist is allowed to be a person first" - some of them might argue, among other things.
So what you have is restricted, stigmatised hetero-femporn, with writers afraid to show anything risky, and the genre that actually shows the shit an edgy teenage girl wants to see - naked, well-drawn dudes with explicit sex scenes and good character/plot writing. Is it really that surprising that so many of them will come to the "I wanna be an anime boy" conclusion? It's the only way they'll get what they want. Being a girl in sex sounds so boring and weak anyway, right?
If they do not poon out, they at least become some sort of non-binary or declare themselves some queer sexuality, just so they could get away from this feeling of being powerless and intimidated. But no matter how they shave their head, at the end of the day they are still just confused straight girls.
There's even "feminist porn" that's supposed to cater to women's interests instead of men.
There are some developments in straight femporn, though. I haven't heard much about 'feminist' porn
(isn't it just a lie made up by porn producers to promote being a porn star as liberating?), but even the rare femporn comics are better now. But the damage has already been done to a generation of women.
There are only a select handful of fandoms where M/M content outweighs M/F
That's a nice way of saying 'most'. Even in fandoms with a predominantly female or gender-balanced cast, such as Danganronpa, men will be paired together far more often. Girls have the honour of being background lesbians somewhere far away from the author's husbands. Before you find at least one real M/F work, you'll have to waste hours scrolling through gay rape fics and...
Reader-insert fanfics, ah yes. It's more of a topic for the yumejoshi thread with how unhealthy it is as a concept too, but I wouldn't call them the last bastillion of straight fiction either. I'd argue that readerfics are more often than not
gender-neutral and are perfect for supporting pooner delusions. Sure, you can imagine you're a woman when you're fucking Satoru Gojo, but let's not forget the poor tif who wants to imagine she's a soft bean gay boy. It is now even infecting newer dating sim games for women, as a protagonist is never shown and is referred to with a they/them pronounce. The developer would have a heart attack if she showed a woman getting it on with a guy in her horny harem game.
it was always a thing it was also a niche within a niche until perhaps relatively recently
It's hard to say exactly, because it's different in every country, but yaoi stopped being a niche in Japan a long time ago. And since the advent of Tumblr, no English-speaking person has remained unaware of its existence. It has grown in popularity over decades and is now forever stuck as the default porn for women.
the case of individuals only liking M/M is also relatively new
As long as Fujoshi culture existed, so did the 'eeeeew het' jokes. Fujoshi prefer m/m over everything else, and it always shows in their art, no matter what they do. They can make a mahou shoujo manga with a mostly female cast and still end up with a BL subplot tumor.
In conclusion, I think BL culture served as a solid foundation for the current year's "I'm anything but a (straight) woman" nonsense. It had a lethal combination of social anxiety about female biology and sexuality and a big dose of stupid dopamine from watching porn where men are actually objectified as women always are.
I think the only way to fight this is the way it has seeped into women's minds - through art. Only by developing alternatives to the first end of the pipeline can we ensure a slower increase in "gay male" pooners.
Thank you for listening to my CoomerTalk.
