This is one of the few problems with not having matchmaking. You're forced to find players (strangers) and go through the motions. The risk of this is getting booted last second because people are rude like that for whatever reason. I had it happen to me on Crota--hard, just about to beat it and boom got kicked. With matchmaking you technically aren't in a fire team so you can't boot anyone prime reason to add matchmaking to poe.