Oh yes, a pox on these farming lamers. After all, it's so easy to heal a teammate as he earns an achievement.
Or join a game a friend is in and heal them.
Or be the first person on your team to go medic after someone calls for one, then heal them. That'll be real easy now that there's 6 medics running around on every team...
The bottom line is that almost all of these achievements are so ridiculously hard and circumstantial, and all to get three measely weapons? I can only imagine the kind of frustration people would have trying to be there for a one in a million moment these things ask for, try to earn them, then get killed or have some sniper way behind them screw it up.
I had no qualms breezing through Call of Duty 4's multiplayer challenges for my golden guns, and if I played this game anymore I'd be probably be hard at work right now.