There are still great use cases for using JS to handle animations instead of CSS, such as creating novel, dynamic images or 3D models in a canvas element (particularly when you want it to be interactive in anyway) or to animate SVGs.

My understanding of CSS animations is that they are particularly optimized to run more efficiently and it’s also helpful that it runs outside of the JS runtime, which frees it from any errors in the JS or it adding to the CPU load that may already be chugging along on the page.

Additionally (and this is old info so it may be outdated), using things like `translate3D()` instead of just `translate()` in your CSS will engage the GPU to handle whatever your instructions are, making everything smoother and further unburdening the CPU. This is from my own memory of things I read more than 10 years ago, so it’s possible that even more CSS functions use the GPU at this point, but I’ve not looked it up since.

Anyway, tl;dr: there are performance benefits to using CSS instead of JS for animations.