Well, thats kinda dumb, because its one of many things that keeps people away from the game. There's no reason to not let high level randos just join up on a nightfall for BASIC nightfall runs, terrible puzzles/riddles in their raids as we've seen repeatedly, quest steps forced through Crucible, etc etc. There was no problem with master cores being used for master works, slowing down peoples progress artificialy is all changing them to infusion cores was for. Its their own flavor of " a sense of pride and accomplishment" BS.