Elves can assemble a fast Gaea's Cradle-fueled mana explosion into Craterhoof Behemoth or Natural Order, so Thoughtseize lets us proactively remove a key piece like Natural Order or Green Sun's Zenith before they can race us. Cabal Therapy is less reliable here than direct discard since Elves plays a wide, resilient board rather than a single combo piece worth guessing. Memory's Journey is low-impact against a creature-based combo deck that doesn't rely on graveyard recursion, so it makes room for the extra discard.