What's the point of React if SSR (other than SEO)?

Question

React

It is clear that SSR is needed for SEO and other, possibly useful, things, but then what is the point of it if everything is still rendered on the server like in the most ordinary PHP site?

Answer 1

SSR is not for SEO. Modern search engines are quite capable of running JS on pages, loading data via AJAX, analyzing transitions from historyAPI, and so on.
SSR is needed primarily to speed up the initial launch. The bottom line is that the user receives an already formed page at his request, he does not need to wait until the data is loaded and displayed on the page, he can immediately consume the content. But after loading the site works like a SPA.
That is, with SSR, each page from the server is not loaded, only the first one is loaded, but exactly the one that the user requested. Subsequent pages are already rendered on the client, and the server only sends data.