The problem with the PVP leaderboard is not that there are people on or near the top of the leaderboard that are (allegedly?) cheating (please note that I am not trying to accuse anyone!). I have not personally collected or seen proof of cheating, so I make no judgement. My personal belief is that there must be rampant cheating going on there, considering the insane amount of battles being fought weekly by the same players. Either they have no life outside of GoW and can afford to spend 8-10 hours each day playing GoW or they have some advantage that others don't have (botting or account sharing) to reach those numbers. but again, that is just MY OPINION.
But that is NOT THE PROBLEM!!!!
The problem is that the leaderboard is based on cumulative stats, which makes exploiting just too easy (botting or account sharing). And there are always people that just can't help themselves and cheat if the barrier is too low. Now I believe @Sirrian if he says that the devs are actively trying to hunt these people down and banning them, but the last few months the number of PVP points gathered by the top of the leaderboard has grown to insane proportions. This may be due to the fact that the attention of the devs has been on GW and the shift to Unity, but I really hope that their attention shifts back to catching cheaters after GW is out.
GW may be new content and a source of revenue for the devs that catching cheaters obviously is not, but that does not mean a clean game (i.e. no cheaters) is not every bit as important for peoples enjoyment of the game as new content is!
All just my opinion, of course!