I've thought this too, to some extent. The thing is though, twitch has a lot of young viewers. I don't know the numbers but I'm sure ther are also a lot of young men. This kind of behavior can be predatory (it's debatable how much I blame the streamers for this), and can install some anti-social beliefs about how relationships with people work.
To be clear, I don't think this is something that should be banned, nor do I think it's something that we make compromising laws for to fix.
I think Twitch knows what happens on their platform, who their audience is, and tries to have it both ways: one where it's a platform for everyone, and one where you're encouraged to pay money to watch someone "practice yoga" or stand in a hot tub. I don't think culturally, we should be passing that off as a "normal" thing to do.
If you're an adult who wants to pay titty streamers all day, and have a healthy understanding of the whole situation, that's your business 🙂