You know I have also been thinking about the word affiliate here and if this is your curiosity and view that means my thought wouldn't be far from yours then. I'm thinking maybe like an a agent, subsidiary that intercept between to get a final result or satisfaction but I think more clarification will be needed here, thanks.
I don't know how to explain this but basically people can earn money from affiliate program because if they can get new players to deposit and play usually they will get particular percentages from players deposit and indirectly those people already help the gambling sites to get new players so between people and gambling sites are can get benefit each other