I have no info to explain that, but Id love to hear the science about it if someone can explain it
Using her in this format allows her to partner with a Background, giving your Commander deck a unique flavor that opens a larger card pool for you to play with
Mixed with the right creatures, it can be the heart of a powerful combo deck: Yawgmoth, Thran Physician, plus two undying creatures (for example Geralfs Messenger and Young Wolf) generates a Yawgmoths Bargain sort-of engine, that can be turned to a One Turn Kill adding a Zulaport Cutthroat effect to the mix
Again, in this very digital game, they aren't actually protecting anything from getting scratched, dusty, or bent
You want to cast this late in the game, when it effectively doubles your board state thanks to convoke
The answer hardly matters if Heliod's Intervention is in the conversation, too