Judging by how often people forget to place break;, it's much more natural for us to think of cases as exclusive.

I dunno -- remembering to add the break; is just one of the things that I know and will never forget when I write C. You can call it a feature or a bug, but it's part of the language that I know.

I didn't write the node to complain, really, it's more of a warning for anyone else who grew up writing C. And it's spawned a couple of really good responses detailing alternative approaches that work, both before and after 5.10. And that discussion, by itself, is very useful.