Even if react is made for SPAs (which is a murky definition anyway) there are many parts of react that make general website development better. For example dependency management is way easier and maintainable with npm/react than manually importing scripts in the right order the traditional way. Achieving high levels of interactivity is also much easier for the same reason.
Just because react was built for one things doesn't inherently mean its wrong to use it for other things.
Just because react was built for one things doesn't inherently mean its wrong to use it for other things.