Some ppl prefer teamplay while others only frag,they are just different playing styles.Same goes for ff on or off,you have to adjust to it.I play both styles servers,if you seperate the servers I would have to manage my rate on 2 seperate score boards.... :s.
I know plenty of players who score awesome on ff/on servers,although they're maybe not on top of the list.Maybe it's the fact that on ff/on servers you get less beginners so scoring is less high due to the quantity of advanced players,just saying...