> A really key one being that React effectively handles the rendering tree directly, and can therefore do high-level manipulation and performance work on it, whereas Windows paint messages forced the windows themselves to handle all of their state diffing and painting issues.

That is a big difference. I think we should pay more attention to things like who-owns-what when we're thinking about the structure of our applications. It's a bit glib to, as the author of the piece does, say "oh well there's diffing here, and Windows had diffing too, so they're the same". Differences like this, well, make all the difference.