Kantor on 02 October 2012
You're looking at it the wrong way.
It's not graded on a curve. A 5/10 isn't average, it's mediocre. Because of the high cost of developing games, the average game is much better than mediocre, and probably all the way up to decent around 7/10.
There are worse games out there, but nobody reviews them and nobody plays them.
The review score is not a replacement for reading a review, it's just an at-a-glance way of reconciling positive and negative statements to get a very quick first impression of whether or not you should buy the game, and it makes average calculation possible.
(Former) Lead Moderator and (Eternal) VGC Detective 
