That's a good point. At the same time, I believe it can make a lot of sense, particularly if it is used to implement functionality that was previously implemented in JavaScript.
Given that CSS is not an actual programming language, browser vendors can optimize it in ways that JavaScript can't. This extra optimization is a big benefit in the world of mobile devices and batteries.
I'm constantly amazed by how much can be achieved with only CSS nowadays. It seems like it's getting more powerful by the month as developers find new and tricky ways to push the boundary ;)