I have seen a good number of people benefiting greatly from referral programs and mostly those that have people that wager a lot under them are the ones making the most out of referral programs and if you see anyone complaining about referral affiliate programs being a way of times it means there have not truly and entirely taken part in the affiliate programs the way there should and that is affecting their earnings.
I have seen some people that have only one down as affiliate marketers and they are not making any attempt to make any improvement to that situation, this could be the reason why some people see affiliates as a waste of time.
Casino platforms typically allow affiliates mainly to grow their business. A person just referred and earn is not possible in casino platforms. As you said everyone will have wagering requirements as well as their minimum deposit amount. There may also be other requirements. A person is eligible for referral bonus only if all those conditions are successfully fulfilled. Affiliates can easily gear up a person's earnings but referring without the terms will only be considered a waste of time.