Maybe the casino owner or the team had already understand that referral are being abused nowadays and also it is not worth bringing because gamblers had their way in finding good site and not just by clicking those links .
and also the internet world are becoming wider and wider now, competitors are popping from here and there so maybe the competition will arise by how they are being mentioned by actual players than just by affiliation .
If the casino owner finds out that a referral is being abused, they can tell the person who spread the referral that it was wrong and warn them not to do it again. If they are still repeating it, the casino team may freeze their account until they understand their mistake. Gamblers responsible for spreading those referrals will surely know how to spread referrals properly so that they can get new people to click on those links and join under them.
Competition in the gambling business is indeed very tight, and players who spread affiliates will choose a casino that can provide benefits for them. And if they can get some extra income from affiliates, they will keep trying.