There is very likely a person or group at Amazon that considers this a feature, at least when product commingling was introduced.
In an ideal world with no counterfeits, product commingling is an efficient thing to do, and if a product is commingled, there is no point in giving the 3rd-party seller top billing, the customer should feel like they're buying from Amazon.
In an ideal world with no counterfeits, product commingling is an efficient thing to do, and if a product is commingled, there is no point in giving the 3rd-party seller top billing, the customer should feel like they're buying from Amazon.