I remember when I first started to try and learn React there was only a handful of words and a vague diagram from Facebook about its Flux architecture. And after that there were many, many similar state management libraries. That some in the community picked a smaller one that had in-depth documentation and emphasized stateless / functional style programming is not terribly surprising.

IIRC there were a lot of comments about having to pass props to children constantly (without using a state management library). Seems like it's a lot easier to not use a state management library now that an official, non-experimental Context API exists. But remember, this was only added a few years later.