Because anime turns you gay
Actually mainly because its socially acceptable in the anime community for women to sexualize women, even if you're not gay, which leads to an average higher rates of lesbians and people free to discuss their likes for hot women and yuri even if irl they date men. General society is either homophobic or too much your sexuality is your entire identity, which makes it seem in comparison as if Vtubers are overly gay (well it is higher than average) or "faking" being gay, just because they are in ships with someone of the same gender or sexualizing their own gender isn't really "faking", that's just having fun and you don't need to care about whether you date men or women irl to do it, prudes in offline society care too much about whether people are actually gay or not, really it's actually more authentic of people behaving like they would normally if there wasn't the social stigma of "you can't express like for your same gender because then you MUST be gay and MUST date them" instead of people having fun and expressing themselves.