Why suddenly all the negative reviews are deleted from a particular movie page

Just that. I went back to see my review on the middle eastern movie "a hero" and now all I see are the fake positive couple liner reviews. With all the lower-rating reviews (which all were voted as top/most helpful) deleted overnight. Every single review is deleted, just for the fan mail 10/10s to remain. This is in my honest opinion plain disgraceful, why do you even have a review feature if you're not tolerating polite criticism, specially when there is a consensus on those negatives among most viewers (shown vividly by the helpful upvotes). I knew IMDb reviews aren't nearly as deep as other communities, now I have learned why...