Except that it's not only a view renderer, it reacts to changes in state, and it has ways to do stateful thing after a component is rendered or stops being rend

Except that it's not only a view renderer, it reacts to changes in state, and it has ways to do stateful thing after a component is rendered or stops being rendered or at other times. And in practice some state is specific to some component or group of components and some state is global or the group of components doesn't translate to a subtree of HTML's tree structure. Also the kind of thing that has to happen based on what happens in the app is often deeply async. And it all becomes a mess. But it's still not as bad as a mess as without React, I believe at this moment.