Milling sounds attractive because you get to "destroy" many of your opponents cards at once
Instead, it simply powers up every card with the ability word once you've turned enough of your lands, spells, and permanents into fertilizer
For example, in Strixhaven: School of Mages, the basic land slot was instead replaced by the Mystical Archive card, which could be uncommon, rare, or mythic
This means that Kida, Royal Warrior can provide some much needed defence early on to protect those cheap and weak characters with useful abilities: such as steels own Razoul, Palace Guard - which has plus two willpower when undamaged - or emeralds Morph, Space Goo or sapphires Scrooge McDuck, Uncle Moneybags
Yes, you can tap a treasure without sacrificing it