(We will be back to the Ice Age world later, though)
You make extensive use of the graveyard as a secondary value engine, with a number of cards that utilize abilities like flashback, encore, or escape to keep you flush with options
Not only that, but you can use Ulamog to destroy their best permanent before that, making the decision of what to sac even harder
Wizards can't make new, expensive cards as quickly as it wants to reprint expensive cards, and the lack of expensive cards to reprint would necessitate changes to increase the amount of reprint equity if Wizards intends to continue reprinting cards at anywhere near the pace that it has been for the past year or two
While card selection and card advantage are two very similar concepts, theyre strictly different when it comes to the outcome
The copies are put directly onto the stack