The process in that doc provide the primitives on which SSR can be built. Vite-plugin-ssr is one such implementation. It provides a rather "NextJS-like" experience out of the box. Although, it allows for very easy differentiation between server vs client. (a file naming convention). It's not an attempt to clone NextJS and the documentation should make that clear. It even gives references for other projects that DO attempt that goal. If you currently have a home-grown solution, this is definitely worth a look as it could solidify some approaches to the SSR problem.

My only issue with it was (when I used it last) I couldn't get it to easily just output an HTML fragment. It kept trying to wrap my output in a full HTML doc (with a <HEAD>/<BODY> etc). That's one of my major contentions with NextJS as well. Often my webapps are used in the context of a larger document (sort of like Micro Frontends).