Fable of the Mirror-Breaker is everywhere, and most matchups have at least a couple important artifacts or enchantments to get off the board
Therefor nothing can block them
Its still used that way in Premodern, Vintage, and Legacy, adding spice like Kalastria Healer or Spike Feeder of all things in some builds, and looking to infinitely bounce your creatures for Grapeshot in others
With this ability, the player either gains a three-card advantage, or drags their opponent toward slowly (but surely) milling their decks, which leads to an instant loss if the opponent has no more cards to draw at the beginning of their turn
One-mana removal is hard to come by in black, but it still usually didnt do enough, especially when compared to cards like Tragic Slip and even Ghastly Demise