Sure, but where is your data and business logic going to live? If the answer is "just write it in JS" then it's no longer a question of "just use React" but "let's replace our entire stack with Javascript".
Ya it really depends. I like redis and Postgres generally speaking for data, and Ruby on Rails generally for business logic. And you can certainly do universal rendering with that easily with react_on_rails. If you do end up needing more perf, maybe go would be interesting.
Yes but we're still going a long way from "just use React". One benefit of the "JS sprinkles" approach of Turbolinks+Stimulus is that you have a far simpler and more productive stack: Rails (or other framework) renders templates with some minimal JS on the frontend, as opposed to the inherent complexity of API + SSR + SPA. There are occasions when React is a good choice of course, but let's not underestimate the costs of the SPA architecture.
Why would the entire stack be JS? Even in server side React, it can still fetch from APIs, so presumably you have a backend to fetch from, in whatever language and database you want.
