At what point the review system becomes a net liability for Amazon? Some of these scams are completely fixable by system policy (the "build up reviews on produ

At what point the review system becomes a net liability for Amazon? Some of these scams are completely fixable by system policy (the "build up reviews on product A, then swap the listing to sell product B instead" phenomenon, bad curation of poorly related products sharing a review pool) and some are definitely fixable with a moderator's banhammer. But if they continue to let the system rot, eventually customers will stop trusting the reviews entirely. Of course, it's not like they seem too concerned with product quality and consumer trust anymore.