I think it more of certain people don't k of how to use hunters. Last night I was running a fresh hard mode crota run and all of the 3 hunter's in the group were horrible. They kept going invisible from lamp to lamp and not shooting at any enemies. Needless to say none of them made it to the bridge. Only me (a warlock using voidwalker) and someone else (a titan) kept making it to the end. Needless to say I was the last one standing and I crossed the bridge alone. Usually when I play with my clan though we have at least 3 of us cross and most of tge time one person is a hunter. So I think it all depends on who player player is and their skill level.