Honestly, sometimes it's feels like a single player game in which many people are playing in the same game space rather than an MMO. In many respects games like Borderlands 2 did group play better. The least they could have done is made phasing match all group members (while grouped). I can understand not having shared objective credit, but not being able to even enter the same phase as a groupmate makes grouping feel pointless half the time.
As someone who plays with the same group of friends all the time, if one of us has to log off it means we all do since if any of us progresses at all it means those who weren't present get to solo what ever we completed in their absence.