>>32259015Believe it or not, there was a time before facecams, when you were considered weird if you insisted on putting your face on the screen when eveyrone just wanted to watch a game. And the first genre where that started to change was horror games. I used to hear "scarecam" more than I heard "facecam," even. It's fun to watch someone experience an intense human emotion like fear, which is enhanced if you can literally see the fear on their face.
People watch streamers to relate to another human being, in one way or another. That's why vtubers are a thing to begin with. People wanna have a facecam, because we relate to one another through faces and showing your face gets people more engaged, but some people don't wanna show their actual face. Hence, anime girl face instead. Seems like your range of expressions being limited to whether your eyes/mouth are open or closed doesn't hurt people's ability to read emotions into your face. And so the chuubas play horror games.
Of course it also helps that there's a "cute girl gets scared" effect for the boys in the audience but that's a whole other thing. 