Because once he is played, you take all of those lost and discarded characters and shuffle them back into your deck, no matter their cost or how long ago they were discarded
Truly, the possibilities for a really strong deck with these cards is endless, but for players who like to Party, Garland at the Chaos Shrine looks like the best scene box to pick up.
Land destruction is so taboo in Commander that players running the likes of Shifting Woodland or Urzas Saga tend to get away with it Scot free
As a Commander or part of any deck, Yuna, Hope of Spira works really well with all kinds of enchantments and some kind of mill/discard strategy that lets you get those expensive enchantment creatures into your graveyard so you can then cast them for free
It does mean that the beloved Pixar characters should eventually join the Walt Disney Animation Studios' iconic cast at some point, however