With PC games there are computers set up as dedicated servers that players browse through and connect to. It's basically a machine on a good internet connection with powerful hardware designed for multiple players to connect to and send data to them very quickly and efficiently. It mostly translates to low ping and low instances of people getting shot on your screen but not dying.
With consoles, you have matchmaking, where you click a button, the game tries to find people for you to play with, it picks one person's machine to use as a host (the server) and makes you wait 60 seconds before the game starts. If the person you're playing with has a crappy connection, everyone suffers. If the host gets pwned and decides to rage quit, depending on the game everyone either disconnects or someone else becomes the host (basically interrupts your game either way). On PC matchmaking (L4D's matchmaking is different from MW2's) if the host has a crappy PC that's even more suffering on part of the players.
Protip: If you're playing on Xbox 360, every game you play online is with matchmaking. On PC, L4D and L4D 2 uses matchmaking to find players, but connects you to dedicated servers. I have no idea if that happens on the consoles.
There is no doubt about it that it is absolute backwards evolution for gaming.
Bad Company 2 DOES feel very console port to me, probably another reason I don't like it as much as BF2. Stoked for BF3, though, I know better than to anticipate a game these days. I agree that it's a totally different game, more like a spin-off of the BF franchise. Like what Renegade was to C&C.
