Create react app drags in about a million dependencies, and I’ve never met somebody able to make a react app work without it. That’s not “simple” in my book, create-react-app is a tool that so many people are dependent on that it deforms a lot of architectures to avoid having to modify it, using proxies etc
How so? You just need to call createRoot and you have react working.
The reason why people use CRA is that it comes with all the tooling required for modern webdev, such as webpack, babel, eslint, prettier, jest, etc pre-configured for you.
Setting up all these tools takes quite a bit of time, but that's not react specific. You would want those same tools for any frontend project regardless of react.
I’ve done react “from scratch” with manual configuration of the build toolchain, without a builder or template app (there's a lot of each around, CRA isn't the only one.)
It's not particularly difficult, but there's no payoff (in any real world use case I’ve had so far) for the extra work.