I made more money as an amazon affiliate than i did selling through them.. BUT, they undoubtedly use the data collected from their market partners to push products.
Sometimes you get lucky though, if you follow a niche that sells through quickly and Amazon sells out, it really is a nice delight when your product is now the only returned vendor - especially if you have some inventory at their distribution centers and can make the prime users happy.
All in all, selling through amazon for me was very.. tiring to say the least. Even though my commerce site had full integration into the experience it just felt so punishing to try and sell through there for most of my products and there werent enough of "me" to go around investing time as i did on a few nich products to make it worthwhile.