Because it's IW's fault for having the server up. Lets say you didn't know the leaderboards will be reset and you got the game early so you played non stop for a few days. You will be ranked one of the highest then it's reset. Big waste of time...
Well I always thought the point of playing games was to have fun. A few days head start on the leader boards isn't that big of a deal. Hell, this is a glitching forum, I bet more than half of us will be boosting anyway.
EDIT: But I do agree with everyone else that this is a stupid idea.