Thanks in particular for the second example: it's a precise idea which can be studied (the former still is too abstract).

> managing the state manually would have been a nightmare

Now, of course, the annoying follow-up question would be "why?". For sure, there are poor ways to handle complex states without React, but that doesn't mean it's impossible to do it fairly well either.

For example, a divide and conquer strategy might make the situation less miserable already: associate "components" (DOM nodes) to relevant portions of the state only. But it's still too difficult to get a clear idea without actual code (hence my original question: most of the discussions about this are either objectively too hypothetical because they deal with complex/private codebases, or unconvincing toys)