Its very rare that codes actually go live and offer free stuff to the entire community
Warping it for one mana helps you deploy maximum creatures for a big turn, which is helpful when you also need to play sacrifice outlets and as many bodies as possible
If you happened to have disagreed with that statement, Rise of the Dread Marn will make you think twice
You need them to keep your curve low
While there are plenty of substitutes that deal with artifacts and enchantments like Ancient Grudge, Wear // Tear, Nature's Claim, Vandalblast, and Kataki, War's Wage, none of these cards really do what Stony Silence does
If you discard a card while you control Festival of Embers, abilities that function when that card is discarded (such as madness) still work even though that card never reaches a graveyard