The system which is wrong is that people generally rate the reviews useful or very useful this is because of if you want to rate a review not useful you have to give your comments on that review that why you rated it not useful and your comment should be more than 7 words.
Some people only rate other reviews only to earn the category expert badge since it requires the member to rate 50 reviews of a category, thus it becomes necessary for a member to rate atleast 50 reviews of a category.
Thus very less people rates a review as not useful. Thus I believe that this system should be changed.