The problem with multiplayer is that they game never goes the way the developers planned to, this was especially true with the older team-based shooters like Tribes 1/2 and BF2 where big warscapes turned into civil-war like teamkilling practices for vehicles and sniping spots.
This has been partially mended in games like BC2 but still profound (granade/CG-spammers, large volumes of snipers etcetera.).