I think this has been asked since like... ever? At this point, I suppose that Bungie simply doesn't want to implement this option in the game for their reasons. May be everything... from[i] "It goes against our idea of a social gaming experience"[/i] to [i]"We don't want people to rush too easily throught contents by themselves"[/i] ecc. I don''t know tho, I'm just guessing here. [b]POST-EDIT:[/b] I think it's also fair to suppose that maybe they simply "can't" do this without some sort of hard work, like rebuild the entire MM system for Strikes, Nightfalls ecc and this might take too much work with the risk to break everything else. Again, I don't know for sure.