My experience has largely been the same. I would say the biggest mistake some companies make is thinking that the frontend will be "trivial" and hire a bunch of cheap and inexperienced devs.

On the one hand yes, if your bar for the UI is just making it look like the mockups then go right ahead and hire the cheap inexperienced folks. But without proper oversight and experienced developers there, the app almost always devolves into a nighmare.

The stuff you mention I would classify as shiny new stuff. Easy to hire for now and in fact I know a few guys looking to hire exactly that kind of skills. It's going to be different in a few years because by then it will be unfashionably old stuff.

Angular, backbone, jquery were the fashionable stuff ten years go. Who even uses backbone at this point? Their last release was 3 years ago. That's the kind of now unfashionable thing that has probably been largely replaced or shelved by now. They had a pretty big community of users back in the day. Interesting data point if you are looking for one to figure out what happened to all those projects. There are still about 620K downloads per week so there clearly are some projects still pulling that in. But apparently they've not needed a new version since February 2019, which was when the last release was tagged. Good luck if you are hiring for such projects.

Yes, but "needs" is different from "gets". I'm sure there are many places that hire experienced frontend developers, but the rule is that it's more a market of lemons than developers in general, so people jump out with time.