Courser of Kruphix, Heros Downfall, and Languish have forced the older versions of the deck down a path to only need white double white for Elspeth, Suns Champion too far down the line for a dedicated manabase
Players other than you and the chosen player may still perform game actions besides casting spells and attacking with creatures: They may block with creatures, activate abilities, perform special actions, and so on
Abstergo Entertainment is a below rate version of all of those things, so of course its probably a new EDH staple
Its unfair, but thats in the cards name
It only lets you cast spells for free from exile, cast-from-exile is basically a certifiable archetype at this point
Remember how good enchantment removal was in Kamigawa