>why is 95% of Hololive lesbian?
Because if a Vtuber acts like a lesbian, unicorns can delude themselves into thinking they're pure and untouched and the only man they'd be interested in is themselves, and girls acting slutty around other girls is hot. If a female fan is lesbian, they also think it's hot that they're into other girls, and become female unicorns as a result. You're catching both demographics with half of the effort and a fraction of the time.
Comparatively, if a VTuber shows interest in any male entity, god forbid one that could be seen on this earth, unicorns start shredding their merch and buying rope on amazon, and lesbian fans are upset that their straight oshi wouldn't be attracted to them and would pass them over for whatever dude is in their eye. Worse yet, passive fans who build general parasocial tendencies tend to reflect better on a direct 0:1 relationship between them and their streamer, with "chat" being the Royal We addressing their one streamer on-stage. A third party complicates that matter, suggesting that there is an individual standing above those watching, and thus lowering their placement in this relationship, turning the entire chat into a collective third wheel. If you had an NTR-specific streamer, she could do that without any issues, but as long as people watch VTubers and have flowery dreams of being treasured by them, it's career suicide for a female chuuba to even acknowledge a male chuuba.