This is more of a voting, peer-moderation system kind of thing. And it is a new concept that has not be implemented anywhere as far as I know. You might find that useless but then again, some people found infractions pretty useless in the past, inline moderation an overkill, and reputation a nice-to-have, and now they seem to be pervasive in the software today. You are not giving them banning powers, you are giving them a vote on the banning process. Different things.
I do not think it is pointless to introduce new features and new concepts in the software, and I think a lot of admins would use that. I do think that there might be features with higher priority than this, but discussing new things has a lot of value, they might make their way as a core feature or as an add-on eventually anyway.