In one game I'm playing, 4 of 6 players have resigned for almost no reason. This has left me and Hardeep battling each other with 60% of the world being occupied by pointless, dead, ally and enemy obstacles. This has made the game a dreary, painfully terrible and ridiculous game.
Also, in another 4 player game I was playing, I had prepared a decent strategy to force back my two opponents while they were busy fighting the person on the oppositte corner of the map. Unfourtanately, the turn I launched my offensive, the guy on the opposite corner resigned for no reason, and my two adjacent opponents quickly re-routed their armies from the now useless, dead, resigned player to fight me, and I was soundly defeated, lost my momentum, and my strategy was utterly defeated because the other player ceased to exist.
In other words, it is stupid that when a player resigns, they do not become an AI imo.