Id wager many players would rather face an endless onslaught of counterspells (or mass land destruction), effectively locking them out of the game, than see a card previously sitting in their hand pop up on their opponents side of the battlefield
Anguished Unmaking Destroying a threat is good, but exiling a target is better: Those pesky death triggers won't trigger (because exiling ain't dying!), and most decks have no way to profit from exiled cards (unlike cards in the graveyard, which some decks are thrilled to have)
Naturally, it comes from the best deck from the best set release of all of Magic 's history
You can also loot at will, which means Kaito can be a serviceable discard outlet
On occasion, though, he will break his own vows, unable to stand by and do nothing when an extreme injustice is being committed