The one reason for the merit system to be implement was to remove the spam as the spamming accounts won't be able to rank up and those already ranked up will get no current merits. Most bitcoin signature campaign require you to have at least 5 merits in last 120 days.
Even then we see the spam from those poster who have gained the minimum merits requirements. Now whom to blame this?
Of course still the poster, the campaign manager has nothing wrong and already doing their job pretty well.
The mininum merit usually just a rules to apply, it's not guarantee if you receive 5 or even 100 merit you'll not spam. Because I still see some user like that, he get a minimum merit to apply in a campaign but after got accepted he spamming to earn signature quota or burst posting.