Quote from Impossible »Or why we're only worried about that situation in regards to Painter's Servant instead of Mycosynth Lattice or Enchanted Evening, both of which are far more likely to accidentally nuke a game. Other players -- not the person playing the Lattice or Evening -- are far more likely to randomly have cards that interact poorly because playing Vandalblast and Fracturing Gust is just good deckbuilding, as opposed to playing random color-hosers. It really is just Iona.
It was that way for some time but then when Ugin came out there was another kind of scare card. Ultimately I think there is some fear in what it could do with future cards but its a design space that is very rarely utilized. Assembing an artifact creature + a planeswalker isn't exactly easy and to be honest..... why the hell is Iona an ok thing assuming no other card is even with her?