[Greymain]

interesting, so twelve groups on the same quest enter a dungeon? 11 are in a queue? but there is no restriction on where they can go or do in the dungeon while waiting to start the next part of the quest, only that they cannot attack the quest boss untill the current group with the active quest have moved on.
It is quite possible that although unable to attack the quest boss they could still heal or on a PvP server attack the group fighting the boss.

My understanding is that Sigil are hoping the shere size and range of available content will mean there are never more than one or two parties attempting the same quest at the same time.