This is a whole lot of nice sounding theory but ultimately in practice this is just a downright mess to handle in a real application calling the API. If you are using the Angular httpClient for example, a 404 immediately throws an observable error when your app really should be telling the user that there are no results for that query. This crosswires a potential server-level error (broken routing etc) with a request level error in error handling and would make it way harder to determine the cause of the error and lead a dev to just write `status.code ==="404" ? 'User does not exist': ....`

Did I mention that httpClient, by default, doesn't let you get 404 error bodies?

But ultimately, it is all just ideas on 'how neat it would it be to use codes!' when in practice it is so so much better to just drop it and use the codes for more literal values. Imagining a users/{X} as a 404 for invalid 'X' is fun..but like..the server actually defines it as something like /users/:userId and it isn't actually an invalid route and will not be caught by the default 404 handling. It's a conceptual dance.