Imagine that? I'm sure they're the kind of ppl that want to join a clan, so join the only one they can get in, but never do anything, so quit DP. It's not like they're trying to trick people with having multi's in the game, since you said it yourself, they're never on. They never play so they can't hide their ID's.
Plus, we already have enough things, without having to check 800+ IP's of members that never play.