But my point was functions are simpler in all those scenarios, pure or not. Edited my comment to reflect that.
Sure, if you define a function called useWhatever that doesn't actually call any hooks, that might be a pure function. But the restrictions described in https://reactjs.org/docs/hooks-rules.html are not restrictions that pure functions have.
But my point was functions are simpler in all those scenarios, pure or not. Edited my comment to reflect that.