Because Bungie is trash and never listens to feedback. It is clear that the vast majority of players want matchmaking in all activities for all difficulties (as evident by this and other similar posts always receiving plenty of upvotes, despite the few dumb fanboys who just object for the sake of objecting even though they would not be affected), but those stubborn morons at Bungie will never listen to what their own customers want, all while introducing more scams to eververse, and then they wonder why they are bleeding players.