If a casino provides rules or requirements for customer referrals then no one will want to promote their casino in exchange for a referral bonus.
So far, I have never seen any regulations against casino customers who will make referrals to other gamblers and provide referrals for access to the casino.
If anyone mentions which casino provides those rules or requirements I'd love to have a look.
There might some sites that has a bit different rule regarding affiliate program like the one you can see in fortunejack. The main difference is because players cant be affiliate at the same time so if you need to choose between to be player or to be affiliate. I experienced myself there, I was player as well as affiliate in fortunejack years ago. I earned few hundred bucks but unfortunately FJ changed their rules which prohibit players to be an affiliate at the same time. To be frank, I regret a bit because I decided to choose to be a player and closed my affiliate account.