you could prevent reviews of >3 stars to be posted if you return the item. As a legitimate purchaser, you would return the item only if you hate it :in that cas

you could prevent reviews of >3 stars to be posted if you return the item. As a legitimate purchaser, you would return the item only if you hate it :in that case your review is sincere, or if you don't need it that much: in that case don't leave a review. This wouldn't prevent shill reviewers to negatively review the concurrent items, but Amazon could easily identify an account that has a abnormally high return rate + negative reviews and forbid them to review. (I guess requiring reviewers a minimum spending before reviewing would avoid shill reviewers to create an account only for the purchase)