>And the reason that "the code is self-documenting" is a bad smell is because in 3 months even the 'rock star' who wrote it won't remember without appropriate help
That simply means you're working with poor developers.
If you're a supposed "rock star" senior developer doing this it means you're just a bad developer. If you're a junior doing it just means you have some maturing to do.
One is "wtf was I thinking", which comments won't help with.
The other is "where did the requirement come from", and that's (1) not a "cock-sure of themselves" sort of thing; and (2) best solved by putting a tracking number on the commit message, rather than traditional code comments.