Yes, for apps that are not hosted publicly or that are not mainly "websites" – what's wrong with just using react + react-router? So I agree that this is an oversight.
Also, there surely are plenty of non-public web-apps in the B2B segment which run in the browser behind a login or on private networks, where SSR is basically unneeded (also, electron and the like)?
But:
for a public web site or commercial web app, I find the take from the first screenshot pretty nuanced.
It is easy to underestimate the complexity of building your own React SSR- or SSG-framework.
I recently tried out vite-plugin-ssr, which kind of does that, in a way that's agnostic to the frontend framework/library.
Can recommend it for people who want neither SPA without SSR nor one of the established React frameworks.
But for people who want to build a full, public-facing website with SSR (which is kind of a requirement for SEO), with minimal friction, I think the recommendation from the docs is absolutely correct, no?
Plain react for single components in otherwise non-React website, full-stack framework if you build the whole site/app in React.