Here's how I see it, it takes "different" skill but not more. Those who say it does should do some gameplay and actually research it. Halo 3 I think it's 30-40% skill and the rest PURE luck with spawning and timing. Also your weapon over theirs.
COD I think is just camping and one shotting. COD is not really skill, but advantage. A 5 star general has way more perks than a recruit or a colonel so if it came down to it a general" with more exp" would easily win just from a couple little perks, not really skill.
However if a recruit did beat a general then I would put that into the skill category of COD.