Maybe you're thinking more of traditional GUI / UI's? UX is pretty much fad/consultancy/design-driven at this point, though companies also exploit big data analytics in order to annoy the users the most without making them hit "X" (and lately it's anecdotally failing).
That is true for some web sites (perhaps for FB, Youtube and the like Too — feels like it but I don’t know). Activity like you describe is really part of the advertising consultants. But there are a lot of other products beyond web sites out there.
My GF did her PhD work in AI/learning (world looked different in the early 90s) and has been Sr Researcher at Microsoft, Google, LinkedIn, FB, Amazon and didn‘t work on Web sites for any of them. She also worked for some smaller companies, still big, and some of those were web sites but none ad-supported.
The issues ranged from “how do people use this feature” to “how do we find a way for new, different kinds of people to use our product? How can it fit what they want?”
She comes from an era that predates the simplistic approach called "AI" these days. Today it's basically quasi-automated generation of the 80s/90s's Expert Systems decision trees.
A better way to think about it in this context I suppose is that it's all about thinking about the human's cognitive models and how you can 1 - get a handle on what works and 2 - figure out why to be able to reproduce it. A lot of her work for the past couple of years seems to be on the former; a few years ago I would have called her studies "anthropological".
I'm not an expert in this area (though my AI work dates back to that era as well) so am just going on snippets of what she says about her work, none of course which can include anything confidential.
