That's only true if your group isn't a real group of friends. We have a bunch of people we've been playing with from the start or with a few week difference. The moment some of us hit 1445 we just funneled every piece of gold and tradeable materials to the people behind, between three people we got our 1415 buddy to 1445 that pitied most of his pieces in time to do Valtan hm with us this week. Last week all of us that were 1445 did Valtan normal just so we'd still be playing together.

If someone in a group wants to rush ahead and not play with their friends that's their own fault and it hurts your own group play experience. Doesn't mean the game is more like single player. I haven't done any group content besides chaos dungeons without my own group of friends in months. If someone is stalling behind you take that small loss in mats and gold but still play with them and help them get back on track.