why because 60FPS have advantage?

But How to deal with the records of those players who used to play at 60FPS.

At 60FPS the game physics become unreliable and often times way too cumbersome, so limiting it to 30FPS makes the game at least play decently. For people who used to play at 60FPS, there weren't really many and even if so, there weren't any runs submitted at 60FPS to the board.