They aren’t just a game streaming site. “Just Chatting” is a huge category, as is live music

Both of those categories are where most of these girls are, they are the bulk of those categories.

They don't want to be whatever the market calls a porn site. Advertising a porn site is a lesser taboo

I love the weird twitch content BTW, so I wouldn't want to pare down for the sake of risque entertainers

There is clearly value in the experience of being able to see the person playing the game. It might even be inherently important to the gameplay in some circumstances. The whole thing is personality based entertainment for the most part and you get a lot more personality across when you can see the streamer.

I generally don’t enjoy Twitch because of the nakedness (no pun intended)of the business side. Twitch has every aspect of adult cam sites except explicit content and streamers obviously react and are incentives to interact when people toss them dollars but it makes for a poor viewing experience to me. But they are certainly continuing to fumble on where they’re choosing to draw lines on what is or isn’t explicit.

What happens when advertisers do not care about pornographic content?

That will happen if society at large does not care about pornographic content. Which is unlikely to happen anytime soon.

I'd say that is more true of tiktok et al than twitch.