If you find that concept jarring, I think you'd be surprised by how much of security, compliance, privacy, and anti-spam is facilitated in part by obscurity. These tasks are about imposing costs --- ideally untenable costs --- on bad actors; obscurity has a cost as well.

There are times when obscurity isn't OK (notably, when it prevents other good actors from verifying the security of a piece of software), but this isn't one of those times.