Focus is the hardest one, because that can move around really erratically. But even that sometimes has to be done in state. IE11 doesn’t have descendant focus selectors so at my last job I wrote a hook for our dropdown children to dump their focus state into a React context so our renderers could stay pure and not rely on CSS and therefore DOM state.

Just last week I implemented a hook to reposition a tooltip based on the mouse cursor.

You do need to think about DOM state a little when doing these things. But I would argue that’s somewhat separate from the activity of building a React UI. It’s pretty rare you can’t just render purely based on the React state, using off-the-shelf hooks.