IW is slow to patch these things, you're having a greater advantage over others when you do this glitch, you may buy all the weapons/perks, etc. And Double XP, etc.... It's basically like a Challenge Lobby, except you don't get any titles or emblems, or any challenges completed, basically you can get everything, and use it at level 4.
That is ****ed, but awesome glitch at the same time, for some reason, I believe it may get you banned in the future and/or reset.