It is such a better developer experience. My unfinished Three.js game[0] was on Unity a few years ago, but that became unbearable. The modern web platform is too new, it hasn't proven itself to big money, so it's going to be indie games first.

To answer sibling comments: Graphics aren't a limiting factor for indie games. And a Three.js game can be put onto Steam, I'm pretty sure.

0: earth.suncapped.com