I think the problem is that Blizzard pretty much requires you to do quests in a specific order since, I don't know... Cata? So you can't pick and choose anymore. The closest thing you can do is move to a different zone. That's the answer Zygor gave me.

OTOH, the collection quests are much easier these days. Spawning automatically speeds up with multiple toons on the quest and if the quest item is collected off a corpse, generally all the party members will be able to loot the item.