What about making them stick, somehow? If I leave a negative review for a product that later gets delisted, Amazon could flag the account on basis of "deleted

What about making them stick, somehow? If I leave a negative review for a product that later gets delisted, Amazon could flag the account on basis of "deleted product with poor reviews". It could then try and see if there are any substantially similar items listed a week on. If so, ban them. Perhaps even easier, make verified negative reviews stick to the seller's account. If you delist a product with negative reviews, those just transfer over to the seller, so you see a 5-star product sold by a 1-star seller.