^ And what are the chances that every time a farm is detected, they go on to create another one with learned from mistakes from previous folly that resulted in detection? I would say, 100% and this continuous 'improvements' just make it harder to be detected.
I am going to be optimistic and say that chances are 99% as every once in a while, some of those that get caught may get discouraged and leave the forum for good.
As long as signature campaigns are there, this will continue to happen; no way around it afaik.
What's the alternative? To do nothing? It may seem like a whack a mole type of situation, but still, its worth doing as without those who are catching alt acc abusers, situation would be even worse. Keep in mind that they usually don't restrict themselves to let's say 2 accounts that are in different sig campaign, but instead enroll multiple accounts, merit their alts and maybe worse of all, cheat in contests.
Or BMs could be extremely selective in who they hire and afterwards they should also be checking EACH post whether it's in context of the topic, is logical/rational, is not regurgating what was said in earlier responses — so such accounts are never hired and they lose motivations to create more.
The latter seems more feasible, although the higher workload on manager's part and I also expect burnout.
That would maybe work with low lvl spammers, but not with higher quality members, like that guy who had 3 accounts in CM campaign for years (and to stay there for years, you had to be top quality poster).