Funny, my experience has been exactly the opposite.
But [your block cipher] probably exposed to side-channel attacks either way.
Exposed, yes. Exposed to attackers who don't hold the MAC key, no. Exposed to chosen-ciphertext side channel attacks, no. These distinctions matter.
having to slog through people's terrible crypto on a monthly basis
I do this too. But I try to educate people so that they write slightly less crypto.