That's why the pros of one shooter are not the best players of every shooter. You can't just say "Well Quake is the hardest shooter of all time because it requires the most insane twitch aiming of anything, those guys should dominate CS," because CS has so much required knowledge to be good at.
Quake guys would dominate the ARMA scene
These skills might in some sense transfer from game to game, but because each game emphasizes different skills, being good at one game does not mean you will be just as good at another game. Being a multigame FPS specialist (at the highest level) is incredibly rare. It basically doesn't happen.