Anecdotally, I have encountered the latter a few times. I've known older developers (> 40) who didn't want to move to Angular/React and would rather have stayed on jQuery (for complicated brand new web apps) or didn't want to learn beyond Java 8.
Backbone, Marionette, eventually Angular and all the rest were huge improvements. You needed a message passing / routing framework, and the new frameworks have consolidated that and improved on it.
Older developers are sometimes more conservative. Sorry. And age leads to cognitive decline. Reality is reality. I'm an older engineer, and even if things are stacked against me, I'm ok with that. It's a consequence of the brutal shift in cultural education around the craft. I hope more creative individuals flourish.
Be wary. This can happen to us all.
Honestly I think it's an error to assume that everything needs to be in React. Even with Hooks it can be overly complicated for many projects. The new thing seems to be Svelte and I would try to make that work or Vue before going with React even though I know React is vastly more popular.
But you can build with vanilla JS and it can work out fine. Especially if you have control over the UI design and create something straightforward without a lot of state interactions. I mean React is great and can be a good idea for many projects but I think taking it as an assumption is more of a persistent trend than a totally empirical choice.
This right here is the problem. A lifetime commitment to learning, especially when it is inconvenient, is a requirement to be successful in software development.