If that held up in anything beyond the short term then Amazon would have killed their associates program years ago. The fact of the matter is that the associates program may cost them 5% of the sales but they believe it makes them significantly more profit than they would have without it. And, there is absolutely no doubt that Amazon has the stats to back up that belief.

I had the same thought as you, but it just doesn't hold up when you think about it from anything but a short-sighted perspective.

If I were amazon, and people were making apps as cool as Mazo to sell products for me I would set them loose on the world without hesitation. So what if they outshine the Amazon built app. Doing so would result in more enjoyment of a product that drives amazon sales, and provide an extremely cheap form of R&D for what features they should include in their own mobile app / site.