The publish-subscribe/observer/mediator pattern is perfectly fine for state management, and doesn't need a framework. At most, a small-ish library, but you can also re-implement it yourself quite easily.
Reading your comment, I have the impression you took it as "there shouldn't be any state management necessary", instead of "state management doesn't need a framework" sense.
Reading your comment, I have the impression you took it as "there shouldn't be any state management necessary", instead of "state management doesn't need a framework" sense.