That might be a case where you want a SPA + backend API. But the point is that in many cases you either don't need a highly interactive frontend or the frontend is not that interactive (ie. progressive enhancements work).
React has been very stable throughout its life time. You can run 10yo react code in v19x without issues.
Components are backend logic in an SSR application. If we have some component and the associated HTML BS JS, we're good to go. Virtually all backend frameworks have components.
Whats the advantage of this? We have one component. When we use react or vue, we now have two. The backend one and the frontend one, and they're not the same component. We can kind of force them to talk together over JSON and an API.