Because one of the things I look for in new card designs are cards that play in an area that suggests more design space
Ephara, Ever-Sheltering draws her indestructibility from the enchanted fabric of Theros rather than mortal devotion, while the doomed Heliod, the Radiant Dawn lacks any of his previous markings of divinity
Best Buy, Target, Walmart, and other big chain retailers that carry Magic products have deals on stuff in their stores all the time, but whether or not its applied to MTG stuff specifically is anybodys best guess
The answer is that there are certain spells we don't want to be instants not that they can't
And the end result was that pretty much any serious Legacy player needed to carry around a bunch of stickers with them to tournaments, even if they weren't playing the sticker cards themselves, just in case they might end up reanimating or copying their opponent's Blank Goblin