I've been curious about this myself and done a decent amount of research on it. Given how ubiquitous it is in vtubing, I've been able to ask a fair few and gotten their thoughts on it, so I've got what I feel is a solid mixture of first-hand accounts and actual scholarly analysis.
Most women trust gay men more than regular men, because they don't feel threatened by them. The average man can overpower the average woman with only minimal effort, so any interaction between a woman and a straight man always carries a risk that is absent in the company of a homosexual. Women perceive gay men as intrinsically more feminine and agreeable, while still retaining the basic social inclinations of men, which makes them better company than other women - hopefully I don't need to explain why.
Women are
statistically more likely to go to a gay man for dating and relationship advice about another man than either a straight man or another woman (if given equal access to all choices).
They also trust gay men more in nearly all social contexts. The female stereotype of the homosexual relationship is one of passionate spontaneity - a very quick, intense romance and emotional bonding followed by sexual consummation. Women often crave this kind of relationship themselves, as do straight men, but know that it's extremely unlikely to happen due to all sorts of factors that again, I hope are self-evident.
Women also project their existing selves onto characters rather than imagining themselves as said characters. If you wrote a story about a hulking Amazonian woman who dominated men and was physically superior to them, it'd appeal only to submissive men and misandrists. Normal women wouldn't be able to project themselves onto such a character.
Gay fiction on the other hand lets women project themselves onto the bottom partner in the relationship and experience that idealized perception of passionate lightning romance, without the issue of childrearing and societal expectations interfering with the fantasy. They also enjoy seeing men dominating and controlling each other. They feel powerful and empowered by consuming media that depicts those who would normally have power over them using that power on each other, in a way that arouses and amuses the woman.
That's also why cuckoldry appeals to a lot of women, as does NTR or even various forms of extreme pornography like gore, rape and mindbreak. They want to feel desired and fought over because that assigns them intrinsic value as something
worth fighting over and exerting effort to control.
As a side-note, women experience arousal in an entirely different way than men do.
A straight man is usually repulsed by gay porn, while a gay man is usually repulsed by the opposite. Women on the other hand
don't really care about the orientations involved.
The social dynamics of this kind of thing really interest me, because it shows such profound delineations between the psychology of men and women. It's also why I have such a visceral loathing of progressive nonsense, because it completely infiltrated these fields of research years ago and torched treasure troves of objective, evidence-based studies and debates.