The second possibility is Wizards realized they could make more money by making the powerful cards harder to find, going so far as to intentionally put tournament playables at Mythic to increase profits
Similarly, Elemental HERO Shadow Mist can either provide searching when it's sent to Grave, or it can search for Mask Change when Special Summoned, giving you a way of going into your Masked HERO plays
Sword of the Animist only costs two mana to cast and equip, and each time Cloud attacks while equipped it will search for two basic lands and put them into play tapped
Unlimited, the big print run most of us grew up pulling, often called shadowed because of a small design change around the art window
Furthermore, the card's effect is not once per turn, which means it can be used several times if players have a way to get it back from the GY