Something that I really like about React is that it is easy to reason about the state of each component, with functions there was no state, with classes, you can see everything that touches the state there in your class.

I am not sure how having various functions (hooks) that trigger state changes and so re-rendering is going to pan-out in practice.

Here comes setInterval and counter packages, no I don't believe I can simply avoid using them, everyone depended on leftpad, indirectly.