I understand your confusion and dismay over React because I'm myself a backend developer and the kind of complexity doesn't exist in backend tech stack.
But this all or none of it has anything to do with React rather with a broken language design which never imagined anyone would write JavaScript worth more than a few paragraphs in a single file.
That's where tons of bundlers come into play from parcel and webpack to vite.
But then there are some language extensions that must be transpiled before they can be bundled. Your JSX comes to mind.
Typescript can be considered in the same league.
Minus all that - Modern React has a very minimal surface area, very few concepts and that's about it.
But this all or none of it has anything to do with React rather with a broken language design which never imagined anyone would write JavaScript worth more than a few paragraphs in a single file.
That's where tons of bundlers come into play from parcel and webpack to vite.
But then there are some language extensions that must be transpiled before they can be bundled. Your JSX comes to mind.
Typescript can be considered in the same league.
Minus all that - Modern React has a very minimal surface area, very few concepts and that's about it.