@Hal - The scenario I see (kinda combines a couple you mentioned)

That dps that wants to skip straight to the end jumps off the platform no problem. Another dps that doesn't know about that, but sees the parachutes will grab one and jump. He floats off course, pulling the mobs and dieing. The other dps sits there waiting for the rest, except the tank is going the long way.

Now the one dps is bitching and waiting for the others to join (which they don't) and the other has no idea where the entrance is. The other three make it to a boss with careful pulls.The reluctant dps either has dropped or teleported out/in and rejoined him. The lost dps finally found the entrance, but don't know how to get to the group.

The other four decide are trying to explain where they are while standing fairly close to the boss. The one pulls a group by accident but can stay ahead of them. As they rejoin and try to take out the stray pack, the boss pulls and they wipe.

As this is now a solid 30-45 mins in, try to imagine how the rest of the dungeon goes. Oh wait, it doesn't. The tank, healer, and one dps get back to the entrance, zone in, hearth and drop. Another dps rezzes at the graveyard, drops, hearths, and requeue since it will be over 10 mins til he gets anywhere anyways. Nobody is sure what that dps that got lost all the time did, but his spirit was well on the way to Ironforge asking for directions when that last person left group.