If you start reading more of the site, you will see that a lot of affiliates who do not offer rake-back shy away from poker sites that allow rake back to be offered by affiliates.
It just results in your players being stolen by other affiliates who do offer rake back, and who show players how to open a duplicate account.
So It makes sense to decide upfront whether you are willing to pay the incentive for the room, or if you want to hold on to your percentage and stick with rooms that forbid affiliate driven rakeback.
There are both types in the Prima network.