You seem to have a limited understanding as well.
Unlike other retailers, who are front and center that they own the sales data (some even sell it back to you, the 3p merchant), Amazon explicitly states they will not use that data (except in aggregate). Bezos' statement that he cannot say for sure if the policy has been violated is an admission that it has, and is even encouraged. It's very possible and easy in fact to enforce a chinese wall around that data. That they have chosen not to -- that the data is possibly available at all -- means that they expect successful PMs to use it on the down low.
It's clear they have this policy so as to attract merchants. So to turn around and violate it is a pretty severe issue.
Second, Amazon is in a position to actually produce or re-brand products under their own very strong brand. Unlike other retailers whose store brand is always the discount and less desirable option, and generally not taking away sales from the premium product.