1. It's not more stuff to learn, it's different stuff to learn, arguably less. Learning Components is not a prerequisite for learning Hooks. Or perhaps I missed the memo, as I've built an app using Hooks, and still haven't need to learn what 'componentWillMount' is supposed to do.

2. Don't mix Components and Hooks.

3. Agreed, change is hard. It's also the only way to avoid stagnation. In the long term, change wins. Or else we'd be programming in JS1995.

4. Insufficient example. What is the business case for a memoized hook returning hooks? Perhaps there is a simpler design, can't comment.

5. There is no global control flow. There is only per function component control flow, which proceeds from top to bottom. Possibly preempted by a hook/hookfn execution, if my early learning curve is to be believed. Which shouldn't matter if one is thinking in terms of 'pure functions returning jsx', as preempted functions do not return, thus have no observable effect.

Tip: Only change hook state from event handlers, never from render function code.