I'm all for defense in depth but I don't see the point of a redundant cryptographic layer. It's not trivial that it doesn't broaden the attack surface instead of narrowing it.

If the argument is that a steganographic layer that involves cryptography does a better job at concealing than a similar layer that doesn't I'm also not convinced. Cryptography helps against MITM scenarios, but at that point the existence of the service is already revealed.