Doesn't, imho of course. MobX makes creating and using global variables way too easy. One of the more nightmarish legacy projects included hunting down the culprit that sometimes changed some variable in mobx store. Abysmall tooling (compared to Redux) doesn't help either.
Currently my go-to store is Redux Toolkit [0]. Explicit store management, but much less verbose than regular Redux. Also, initial state, actions and reducers are all defined in one place (slice).
'Doesn't' or 'does'? We've found MobX to really help.