those are both team based games..........
but the teams aren't real? They're only video games? Besides, you really think people actually rely on teammates? Good luck. Mike is busy flying jets into tanks, John and Sam are both driving around the far edge of the map trying to snipe people with the Abrams, and loving Sarah is still trying to figure out which button the joystick is.
The point I'm trying to get across, is why does it matter? Let people team, damn, so what. If it was Bushido, Snow and Kalphiter teaming up sure, that would be extremely abusive, but all three of them prefer to fly solo anyways.
In the end, I don't really care if it's a rule or not, I just think your argument is silly. So what if it's a video game, if it's a video game we can do literally whatever we want.