While this cost reduction comes at the cost of reducing the power and toughness of each of your creatures by -1/-1, the inherently sizable nature of Demons causes this drawback to be rather negligible for Demon-tribal decks
If the tap ability gets countered, you sacrifice your Polluted Delta in vain, because you wont be able to search your library for a land
This plays into its other effect that gives all creatures with +1/+1 counters the abilities of all exiled creatures with Agatha's Soul Cauldron
Plus, the Naya colors support everything from Impact Tremors to a powerful finisher like Jetmir, Nexus of Revels (aka, "The Great Catsby")
These shaped the game so much that the upcoming Brothers' War set will retell the events of Antiquities
More on this at the bottom of the article Three Elspeths is also worth noting, and shes been prevalent in many of these lists