You've missed the point entirely. Hooks offer nothing new because their functionality was already implemented in React class components.
They literally add no functionality to React. The docs actually state quite clearly that developers are discouraged from replacing class components with function components.
React doesn't offer new functionality to do UI. It offer new ways to think about the problem.
Hooks doesn't offer any new functionality over `this.state` and component life cycle, it offser new way to think about the problem.
Again, you've missed the point.
You're also misrepresenting what the docs say about replacing class components. They're saying that you don't need to replace class components just for the sake of using 'the new thing'. However if there was some concern you wanted to extract from a class component that you could not previously, you absolutely could adapt it to use hooks, and then extract and reuse that concern in another component.
Could you link to where it says this? My understanding is that hooks are intended to be the new best practice, and ideally all code would use hooks (which the React team believes are overall better than class components), but the React team doesn't want to force migration pain on everyone. So as I understand it, it's not that a class -> hook refactor is "discouraged", it's more "don't let this be too much of a distraction, and don't feel obligated to rewrite old code".