The fact is that 99% of what's done on the web is (mainly textual) document management/display. Facebook (the website responsible for React!) is 99% document display.

The truth is that "rich experiences" are mostly made by enhancing the basic experience of reading rich documents. If you want an inspiring vision of a document-centered future, look at IndieWeb.org. And/or roca-style.org. It's a vision of how the web can be knit together into a cohesive whole based on URLs, rather than segmented into a bunch of unaddressable silos.