I guess redux solves both "state" and "messages" at once, that's good. But what you work with then is not "vanilla react" at all. I don't even think "vanilla react" can really exist, beyond toy examples. You either use frameworks or write them yourself (worse).

Yes, class components.

Function components help in reducing boilerplate code when all you want to do is put together a component that is a thin wrapper over other components with barely any state or logic.

The problem with function component fundamentalism rears its head when you start to add state and life cycle handlers, as you start to pile hooks on top of hooks when simple inversion of control would make things cleaner and easier to manage.

Literally the main criticism thrown at class components is boilerplate code and support for life cycle methods. It turns out that they are a nuisance when writing small stateless components, but are an unavoidable need when you add non-trivial state and life cycle handlers.