You'd be surprised... I did a LOT of cleanup work for a private college that had a lot of "clever" developers that didn't understand static variables in C#, or how the ASP.Net lifecycle worked. Race conditions and all kinds of weird errors when the system got busy. Not to mention a lot of "fun" performance issues.

Just because someone has a CS degree doesn't mean they actually know what they're doing.

That's different, those are clever people who are bad developers. But too proud to admit it even to themselves. You come across them a lot in small/mid sized companies and non-tech IT teams.

Cloudflare's no longer the darling of HN, but they unquestionably have clever people who are excellent developers. Just maybe not excellent at web dev and cache invalidation by the sound of it.