Nice to “see” you again btw Marc. I think the last time we were a little distracted by a blonde bunny girl at the Ice Bar 
On the topic of quotas, I think there are two reasons casinos implement this, for one or the other, maybe both. In some instances, and probably with this one judging from the very swift response I got from Centrebet just now (which incidentally said this wouldn’t be applied retroactively), I think the basic premise is to ensure an affiliate continues to promote them. It’s about “intent” – if I am trying to do the right thing, but unable to for a factor outside my control, I wouldn’t want to think I could be penalised further. Why would I accept those conditions when really, I have a choice in where I direct traffic?
But quotas are the wrong way to go about it as this thread hopefully demonstrates. A fairer way is to offer X commission while the casino is still being promoted, dropping to X% when the affiliate removes it. Even then that requires a fair balance, but if it’s an upfront term that is clearly stated, that seems fair to me. And any % reduction certainly should not be applied to players referred previously to the date of implementation.