It's a bit humorous that often the same people who insist the code should be enough documentation follow that up by clarifying that git, of course, supplies the rest.
So something entirely outside the codebase, which may or may not be available to the person who needs the information, and which may or may not need to be extensively searched through years of history to find the relevant commit message, which may or may not be sufficient to explain the code... is better than having a comment in the code.
sounds great until there's a refactor (including moving code around), then all the "comments" get buried.