I have “witnessed” well over 100 vaults of varying qualities being looted by friends, myself, and randos in my lobby, yet no-one has looted red items from them (I have heard of some getting reds from vaults, but i have no idea how many they have opened). I have opened maybe 40-50 emperor chests and got 3 reds, a mate who has opened about the same has got 2 reds.
I understand RNG implies we might just be mega unlucky, but in VT1 the chance of looting reds was clearly significantly improved when playing cataclysm over nightmare (originally reds only dropped from cataclysm, the way it should still be imo).
Another thing I’ve noticed on Reddit is that there are multiple variants of red illusion as well as reds without any sweet illusions. Reds were so highly desirable not because they were simply the top-tier, but because they were unique and collectible.
I managed to complete the full set of reds in VT1 after putting in well over 1000hrs, at this stage I don’t see myself bothering. I haven’t managed to loot a single red since I opened all of my emperor chests on launch day.