People that says that coh 2 leaderboards need a wipe completely have no idea what they are talking about either that or they mean something else.
A complete ELO reset would fuck up matchmkaing for weeks, low ranked would play vs top players and so forth, it wouldn't be fun for anybody.
This is especially true for a game like coh 2, where there is a low playerbase, not alot of people play on a daily basis.
If you want to get rid of people that sit in top 10 by playing 1 game a month, then simply buff ladder decay or make your elo become "hidden" after a set period of time, having you to play a game before you show up on the leaderboards again. Like IN CS GO.
Oh, and if you cant climb the ladder, L2P 
Exactly, the system just need an more agressive ladder decay. On the other hand...
People who are on the +1000/+5000 just to want to "rank up". It would only mean that the standard would just to be adjusted.