They can't help you in regards to the loot you got.
But as to this happening; read here under the Dungeons: http://na.finalfantasyxiv.com/lodest...ba39b67875a7af

If you don't want to click, one of the bullet points says in regards to Labyrinth of the Ancients (Crystal Tower):

"In the event all but one party member leaves the instance, the remaining party member will not receive loot until they have cast a lot on said item.
* In the event no one lots on an item, it will be lost when all party members leave the instance."