I think the crux of Blladee’s questions was
I understand that all 8 DF dungeons can be ran on M0, but if say a trinket or weapon is hands down the best item for a spec/class, even if it’s just an upgraded M0 item (272 from an off season dungeon), it could in theory be better then a 278 item from a current dungeon season from the vault, thus the rotating dungeon aspect be fruitless for a gear acquisition point of view.