Most games don't reset their leaderboards (or remove people) unless they cheated. Honestly, Idgaf who is on the leaderboard. (That's how I play, I know some people have a different way of playing like competitively)
This idea came into my head while typing: You should at least be lvl 5 before being on the board. 100 kills seems a little overboard. (By then you should've acquired enough kills / deaths to show your skill) The only problem I see is prestiging...
(maybe it's good or maybe it's awful idk)