Having Extirpate be uncounterable means you don't have to blow a counter defending the assault on the opponent's man-lands, meaning that you are still well equipped for the counter battle over their StP's.

Landstill standoffs with Mishra's staring at each other and the first person to make a move giving up some advantage in the process while both people wait to draw a waste or another factory unnecessarily prolong many games.
The gist of this seems to be "my control deck can't beat a 2/2."

What the hell?