Then why is there a 10 point scale? Not saying that any game is perfect, but what's the point of having a scale system when a whole number doesn't get used?
I can't speak for the writer who did the review, but we have given perfect 10s before. I think he just felt that the small annoyances he mentioned didn't warrant a perfect 10, but I agree that 9.9 is an odd score.
Next year will probably go to GTA V :D