I mentioned this in another thread where this came up, but vtubers tend to be ACTUAL nerdy girls rather than the 'nerdy girls' we're all used to. Seems to correlate quite strongly with female autism or otherwise male-brained thinking. Probably why men feel like we have more in common with them, and find them more attractive, even when they hide behind an avatar.

Personally I never really watched any female streamers until vtubers came along, and the thing that attracted me to them wasn't the cute avatars, it was the genuine love for games/anime/books/whatever. Usually I just use them as podcasts while doing stuff around the house.