Having a pressure point against the shops by letting them control what kind of coupons would be shown was probably a big reason they weren’t just kicked out of at least some of those affiliate programmes.
That’s a fair point, but they could have been up front about it, or at least adjusted their advertising some. They basically told consumers “We’ll get you the best deal, and if we don’t find one, it doesn’t exist”, which is a spurious claim anyway, but it surely misled people. They could have just said “We’ll see if we have any coupon codes available” or something less committal. There still would have been a lot of value for regular consumers… if you weren’t using a coupon code, 5% off is better than nothing and if they weren’t being dicks about the referral links, nobody likely would have cared in the slightest.
