[untitaker_]

the problem is that react is being used outside of SPAs, for any sort of interactivity, because it is easy to hire for at this point and because there are a lot of existing components to choose from. so yeah, progressive enhancement doesn't work if the actual component is state-heavy, or the entire site is state-heavy. When React came out, its tutorial was very centered around being embeddable on existing web pages, and it was framed as more of a "jQuery replacement". IIRC the term SPA didn't even exist yet. The other commenter already pointed out what the end result is.

if you don't do it for accessibility, do it for SEO. yeah a lot of commenters here already pointed out that SSR is a thing now, but the concerns you had still apply then. There's two paths to test now, one with JS and one without. This kind of always was the case though.