It's kind of like how moderators don't delete potential scams. I doubt that they would take action against signature campaigns if they were too troublesome and caused some inconvenience. Most YoBit signature wearers have post qualities that are debatable, but good enough to dodge the ban hammer; and IMHO, YoBit is the campaign with the most spammers.

As for signature campaigns without a manager, he's talking about bots counting the posts. Bit-X, BitMixer, YoBit, and a couple others do it.

EDIT: Plus botany's reference.