Dom, that's your opinion.
MW3 is like most FPS games with multiplayer.
Buy it the second it comes out.
Play multiplayer forever.
If you don't, you will be outpaced by everyone and stuck with default guns against hoardes of people who have unlocked everything.
The reason he is saying that they shouldn't play TDM so much is because it's mostly beginners who play TDM.
It's literally the starting grounds, but if they're instantly stuck up against 5th prestige players they're stuffed.