Novice react developers reach for useEffect way too often, because they are still thinking in terms of state transitions instead of declarative states. I have spent a lot of time teaching people not to do that. They always end up very happy once they get it, because now they can build complex UIs and have a solid strategy for compartmentalization, which makes bug whack-a-mole go away.

It's not a fault in the framework, it's a fault in their understanding, where they don't know how to implement features in O(N) lines of code instead of O(N^2).

The hint is in the name: you're supposed to think in terms of formal functional Effects that mount and unmount independently and compose orthogonally.

The result will be a code base that remains maintainable even though you've kept on adding more nuanced features over months and months.

Also, your snippet doesn't cause an infinite loop at all because modifying local variables does not trigger a rerender. If you had written setA / setB, sure, it would... but I think this perfectly illustrates the explicit vs implicit distinction.

Great frameworks don't trap developers in local maxima.