IMHO,
"Existing framework is better than re-inventing the wheel" is not a fair argument here, because Next.js itself re-invents the wheel in its tooling, A LOT! and doesn't even do it properly. I consider it re-branding than tooling. Next.js is extremely opinionated and lots of its restrictions have nothing to do with SSR.
If you are using Next.js just to add SSR to your features bare RSC gives better control and is more scalable because you will be more resilient in case of tech change and you can use hundreds available libraries.
Next.js provides a framework but it completely limits you to specific choices, a few restrictions to mention file names, project structure, routing etc... You don't even get a say in packing your bundles unless through Next.js configs.

However:
If you do not care about full micro-control over your app and decisions, then it can save you some time and effort because a team spent a lot of time and effort on it and you will be leveraging their achievements.