Considering this game's UI is absolutely terrible for learning the game and essentially forces trial and error gameplay into a strategy game, frustration is both natural and expected. For example, you and I know that big AE leads to coalitions. However, if someone just fires up the game, runs the tutorial briefly, then hops into the game to replicate a historical conquest, he'll see "you get 40 aggressive expansion for this". That means nothing without context of everything that AE can do, and the game does *not* provide that via in-game interface, anywhere. It doesn't tell you which aspects of combat are more important (tactics > pips > discipline/morale), so people lose battles and have no idea why. It sure as heck doesn't explain how coalitions work, and you know nothing about separate peace limitations until you see it.
To a rookie just looking to replicate historical conquests on an average difficulty level, the game is both obscure and vexingly punishing when it comes to doing what actual countries did, and in more than one case goes against logic.