Then what the hell IS an adventuring party?
Seriously. Your going to ride out 2-3 days away from the last bastion of civilization (or point of light in 4e), crawl down a hole into a dark, dank, subterranean catacomb full of monsters, traps, puzzles, riddles, weird phenomenon, mazes, more monsters, hazards and obstacles, and still more monsters. And you want to do it with 3-4 other people who you barely know and don't act like a team? You want the mage to cast fireball regardless of if your in the way and the fighter to prefer to solo-kill rather than get into flank with the rogue? Or the cleric who would rather cast bull's strength on himself rather than cure moderate wounds on your -4 hp (thanks to the mage's fireball) PC?
In essence, if your going to put body, mind and soul on the line in a dungeon for gold or glory, would you rather have a cohesive team that works together or an unorganized group of individuals acting and reaction with no regard to his fellow adventurer. I'll choose the latter, thank you. I'll live longer.