Why do nerd fandoms have a sexism problem still?

I’m a nerdy girl and while I try to ignore it I’ve still seen so many different fandoms like gaming, Star Wars, dnd, anime, comics, fantasy etc have inbuilt sexism/misogyny that is still rife to this day. Fandoms have always had their fair share of toxic issues but I’m surprised this specifically is still such a big issue even in our more progressive society. Surely most fandoms would have grow up by now and held less biases compared to before. But nope. I’ve seen many older fans get upset about how their beloved fandom has more women in them now and that they’re ruining it for them. Like seriously what is up be with that logic?
Why do nerd fandoms have a sexism problem still?
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