Consider it this way: Snipers have 3 less perk slots that are available to them, because quickdraw is on every single quickscoper class in Ghosts. Quickscopers often don't use lethals, tacticals, or secondaries for this reason.
Plus, the best quickscopers in the world have a KD of about 1.7 - 2.0, when the best MLG professionals out there have upwards of 3.0 KD ratios.