This is exactly its origin and function among (mostly straight female) readers in Japan, and the intent of the female mangaka who first created the genre. It lifted the readership out of the pervasive male gaze and gave them a space to explore erotica away from the daily expectations of Japanese gender roles, which are still far more traditional than in the west.

Yes, and I think that was a lot of what appealled to me about slash fandom when I first discovered it and got into it (again, this was in the 90s, right around the transition period between it all being zine circulated and starting to appear in heavily moderated, membership-limited email lists and websites.) I was in my mid-20s and had a lot of insecurities and questions about my own sexuality...some bad experiences with men had made me lose all sexual desire for them and I thought I might be gay, but was having a hard time finding women I connected with on a sexual and emotional level as well.

In reading slash, I was able to reframe how I looked at the male body - looking at it from a female gaze instead of a male gaze. I could work out some of my own issues and questions by writing with that disconnect of writing from a "male" character's POV. And, it also introduced me to, at the time, a really wonderful community of women who were creative, intelligent, and (largely) open to those of different sexualities and just, well, generally outsiders or those who felt like they were. (I ended up realizing and accepting I was bisexual and while I won't say it was all due to fandom, my time with people in that community definitely helped me explore and accept my sexuality.)

I never cared for yaoi or got into Japanese fandom because I didn't like how it seemed to push m/m relationships into overtly stereotypical weepy-uke/strong-and-stoice seme roles. (Not to say some slash wasn't guilty of the same thing, but it wasn't necessarily a "mandate" of the genre to do so.)

Anyway, I just have seen the shift in really the last 10 years to increasing "wokeness" in fandom, a push away from it being accepted as a safe space for women to explore fantasies and sexual ideas to a place where one can only do so if you are doing it in an approved fashion. "Genderbending fic" is now offensive to trans individuals. There's either not enough representation of characters of color, or white fans are not supposed to attempt to write POC characters because we can't properly do so correctly. In one corner of fandom you have "antis" calling out people who write about two adult characters who happen to have, say, a 5-year age gap as "abusive", and in another you have fans decrying their "right" to write what's basically childporn. And as this post started out, more and more of the teen girls who are in it have taken their interests in yaoi and slash to the point of deciding they are, in fact, gay men and transitioning to be more like their favorite characters.

In the old fandom days, older women in the community would "mentor" younger fen into the ways, customs and etiquette of fandom. Now, teenagers and twenty somethings are quick to call any of us older women "creepy" or "pedos" if we interact with them at all on Tumblr or elsewhere, and that we need to leave them alone and get out of fandom because "it's meant for young people only."

I don't know what to really say or do about it, beyond sitting in my cranky fannish dinosaur corner with my old friends bitching about these young kids we want to kick off our lawns.