I mean, I am a big SPA framework guy. That's pretty much the main thing I use, day-in, day-out, because most of the projects I'm working on are complex enough that simply hand-coding the entire UI will not work.

And, while only a minority of projects are that complex, those projects are the ones most developers are working on. Most other projects are probably better served with a wordpress install and a bit of theme customisation. Which means it's going to be a minority of developers who work with the very minimal things that are sufficient in these sorts of cases.