[bayesian_horse]

If you need to achieve the same functionality and maintainability without React (or some other external library), then by definition you somehow have to reimplement much of it yourself. And no, React isn't all that big in terms of functionality or size.

What are the chances that you are arriving at a solution that is better than React? That other engineers have no trouble understanding and maintaining? You'd have to invent new concepts, or at least call them differently, to not copy React's (or any other framerwork's) concepts or ideas. That would make it harder for other people to understand the code.