Izzet Spellementals' threats like Hearth Elemental (mana value 6) and Eddymurk Crab (mana value 7) are far too big for Requiting Hex, which only destroys creatures with mana value 2 or less, and none of their creatures are that cheap, so both copies come out. Duress proactively strips their protective cantrips or countermagic like Spell Snare before they can use them to protect their engine, and Maelstrom Pulse is unconditional removal that can answer Hearth Elemental or Eddymurk Crab regardless of size. Shoot the Sheriff is clean instant-speed removal for those same creatures, since none of them are outlaws. Stir Up Trouble's extra cost is risky against their efficient tempo curve. Requiting Hex also can't touch Ghost Vacuum, since it is an artifact and not a creature, so there is no reason to hold a copy back.