I don't see how First Person Shooters are any different from MMOs: they still rely on not getting hit by the enemy by moving yourself away from wherever they are aiming, or backing off to avoid their grenades. The inferface is different, that's really it.
See? I can also reduce all combat systems to 'don't get hit by the enemy'.
See? I can also reduce all combat systems to 'don't get hit by the enemy'.