Izzet Spellementals' real threats (Hearth Elemental, Eddymurk Crab, Sunderflock) are mana value 6+ on the battlefield, so cheap, low-impact removal is largely irrelevant against them and the deck should lean on efficient interaction that trades well with their early cantrips and small creatures instead. Torch the Tower is useful against their rare small permanent like Ghost Vacuum and can snipe a Colorstorm Stallion post-board. Glorious Decay's artifact destruction mode hits Ghost Vacuum, and its graveyard-exile-and-draw mode disrupts Hearth Elemental's cost reduction by removing instants/sorceries from their graveyard. Deadly Precision and Rottenmouth Viper are too slow and too narrow against a deck that wins by overwhelming with a single giant threat rather than a wide board, so they're trimmed for proactive, flexible answers.