Agree with you that the affiliate program is very good for helping to bring in visitor traffic. I don't know why many casinos cut bonuses in that program even though they could have cut other programs, for example deposit bonus programs or other bonuses so they don't cut affiliate bonuses because that will create traffic too decreased, unless indeed they get casino traffic from other campaigns but I also think this affiliate program is very helpful.
The deposit bonus may not be removed from BC.game, because this promo is the most used and new members will trying the service with this bonus. When this promo is stopped, i don't think people who become affiliates will be able to get new members, even they get, maybe not for long time to use. Therefore, bc.game sacrifices their affiliates program, this is also not a good move, an affiliate is an unofficial marketing team for most businesses. And affiliates may be more effective in bringing gamblers to join than traditional advertising.
You are probably right that affiliates usually promote a service pretty well, and even if they do it for their own benefit since they earn money when someone joins under their link and uses the platform, the platform still benefits more from it since they get more money from those users invited by affiliates than how much commission they pay the affiliates.
A platform closing down or making changes in an affiliate program will surely affect its growth if they have affiliate workers who are bringing a lot of customers every now and then, they surely need to revise its program so that its affiliates don't switch platforms.