Reddit already supports this for upvotes; some subs hide the upvote/downvote numbers to prevent exactly this kind of thoughtless pile-on. I wish more did. I think it's usually "for the first <duration> after posting", but I presume it could be made permanent.
Side project idea: HN/PH where the ratings are hidden. This way you still get the curation bit, but people are free to make up their own minds about your website.