What short-window PnL rewards
Over seven days, the highest PnL is usually produced by the largest risk that did not fail. Survivorship makes it worse: the accounts that took the same risk and lost simply vanish from the top of the board, so the ranking is a list of winners from a bet you never saw the losers of.
Percentage-return boards have the mirror problem: they favour small accounts where a single trade produces an implausible percentage that cannot be repeated at size.