> My motivation came from GraphQL as it responds everything with 200s, and so far it has been humming along fine.

This is slightly annoying though, as other consumers (like `fetch` in JavaScript world for example) behaves differently if there is a error. If every status is 200, suddenly you need to manually check the response inside the returned promise, while if you answer with a correct status code when the server encountered an error (5xx), then it'll jump to the `.catch` part of the promise chain instead, which you're probably already handling anyways.

Similarly with curl if I'm not mistaken (don't have it in front of me). A 2xx would make the process return 0, while a 5xx would make it return non-0, so you can handle errors without having to read the actual response.