Deletion is not the only option. They can weight the contribution of reviews to the overall score. They can weight the display order of reviews on the product p

Deletion is not the only option. They can weight the contribution of reviews to the overall score. They can weight the display order of reviews on the product page. They can weight the display order of products in SERPs. Assigning reviews, reviewers and sellers a "fakeness probability" allows you to do all sorts of subtle, useful stuff that clearly isn't being done right now.