You don't, but it makes it easier to integrate in to some existing code. Usually these libraries are written for personal reasons (eg needing it yourself) and then open sourced. If you're making a React app at the time then it ends up being a React library.
One day I'm going to 'un-React' Neon (see my other comment), but until then it 'needs' it.
One day I'm going to 'un-React' Neon (see my other comment), but until then it 'needs' it.