Today, were talking about flurrya mechanic youve probably already built around without even realizing it had a name
Assuming you are playing other creatures (although some of these decks play very few) and some spells that cant be flashed back as well, the chances of having a relevant spell in your graveyard are not that good (and relevancy isnt all about whether its cheap enough to cast, but also whether there are targets)
Also up there are Amulet Bloom, Grixis Delver, Jund, and Infect, four other decks that have high GWPs and also very respectable 4-0 finish rates
As long as you're in a format where you can play Fetchlands to fuel your graveyard, it's essentially an upgraded Llanowar Elves that can heal you and damage your opponents without having to go through their creatures
Theres been a surge in the value of Pokmon first edition cards because they were the first print runs for the U.S