I saw brad's argument as being that in CoD type games the only influence you can have on your team is the shooting and killing of dudes. Even in domination modes you will have to be shootings guys to attack or defend a point.
Other games like TF2 and PvZ:GW have ways to still contribute if your not all that good at shooting via healing, or being a distraction as a tank or by completing more involved objectives.
Co-operation and teamwork can work across either so that's neither a positive or a negative thing for either side.
I think he is influenced by DOTA 2 where you can help your team in countless ways that aren't just getting kills. Maybe I agree with him because I play Dota too, but it is just inherently more interesting, as the shooting people is still in all the games which have more variety in the ways you can contribute to the team anyway.
I think maybe Jeff saw it as an attack on something he likes and he very aggressively defends the things he likes.
This is the first time I've gotten to Olmec, and I even have the necronomicon, visited the city of gold and actually got passed 4-1 for the first time. I'll be quite upset if I literally just have to kill myself!