I know a thing or two about HTML, CSS, DOM scripting, accessibility etc. (which I’ve worked on since the IE6/Firefox 1 days), and still find React and Vue to be worthwhile tools.
Of course they can be used in less than stellar ways, e.g. used at all when plain HTML would be preferable or used to generate a non-semantic DOM. But that’s nothing new, as we’ve seen plenty of nightmarish HTML, CSS and vanilla JS too. It’s disingenuous to contrast competent uses of static HTML to incompetent uses of React/Vue.
I would also suggest that every time I’ve seen an awfully inaccessible result, it was because backend or “data flow” developers with no UI skills were tasked with building UI, in order to limit costs. I’ve seen plenty of ASP, Java and PHP developers producing crap HTML out of necessity (being tasked to do something you don’t master and don’t enjoy). Of course JS developers working with Angular, Vue, React or whatever (including vanilla JS) will do similarly bad.