I've had a good time with react SSR and SSG particularly when using next.js which does a great job optimizing out of the box, but really SSR and SSG are functionally just glorified string interpolators so anything will do. What matters is ease of use and with the strong community and toolset available to react I've had no trouble setting up react for SSR/SSG.

Where things still need improvement is with hybrid apps that take SSR/SSG pages and hydrate them to be ready for the client to take over, but that's always been a pain point, and while we're still not where we need to be I do think it's better than it's ever been and we're on the right track to cracking it.

Maybe it's because I've seen how bad things can get that I'm appreciative of what we have. After experiencing frameworkless jQuery spaghetti code, overly complicated monoliths like angular, and overly simplified micro frameworks like backbone, I'm really happy with the frameworks and toolsets we have now, and react's ecosystem is very mature.

I would say that react is overkill for SSR, but pure SSR is pretty simple so react is also able to handle it just fine and elegantly as react is even easier to use when you're not dealing with dynamic state, and if you find the need to introduce some hybrid client side functionally, which pretty much always happens eventually, it's a good thing to be on react.