I still think the solution is the one I've outlined above - ban the spammers, punish the campaigns, punish the managers.

Deleting individual posts in isolation does nothing. A sig spammer is always incentivized to make more, and can churn them out just as fast as we can report them. If you start doing something which will actually affect their income - temp bans - then they may be motivated to change. If after multiple temp bans they are still not motivated to change, then a permanent ban provides no loss to the forum.

Managers similarly have no incentive to clean up their act. Properly moderating their participants and monitoring post quality takes time and effort. Why bother doing that when you can just put in the minimum amount of effort can get paid the same amount? There is literally no downside at present to them doing this, since they are never punished for promoting spam. Start handing out temp bans to managers not doing their job properly, and they become incentivized to weed out spam and spammers.

And the worst of the worst campaigns, such as Yobit, can be banned from the forum directly.