It could lead to lower prices if they are indeed replacing referrals. Supposing the retailers notice that this is a huge affiliate, basically understand what's happening, and negotiate a smaller commission for these programs (they obviously have a lot of negotiating power since they aren't really getting referrals and could just ban these programs, destroying them), they might have a lower overall cost.
I imagine people running affiliate programs have heard of rakuten, for example, so I suppose they have some reason they haven't banned it (i.e. it actually benefits them/lowers overall costs).
