My understanding is that features of react now require a meta framework to function. The main feature being React Server Components. There’s a bit of wiring things up required that doesn’t happen off the shelf when you add react as a dependency.

To keep CRA working, this would need to be added. Rather than go down that road, I guess the react maintainers preferred to recommend Next.js which offers RSC support.

I’m probably missing some details. This is my general understanding