have you ever played a multiplayer game with 13 people in europe? in mp only mulitary factors matter and diplomacy between players. your diploannex cost to save ~250 dip points for land power is such a waste of slot.
What in the world does this have to do with my post?
Also, I have not played MP. I have no interest in MP. I find the game system poorly designed for a rewarding MP experience. There's too much random chance for it to be a meaningful game between players, which completely washes out any difference in skill. (And several changes they've made, like longer truce timers, only reinforce that effect).
Most players only play SP. The game was clearly designed (originally) around SP. Stop ruining SP for MP 'balance'.
Finally, there's no need to balance MP. The large MP games will get balanced by player diplomancy. Nations have no need to be balanced against each other, because players can gang up on nations which are or become too powerful (and should!).
If I was going to play a MP game of strategic conquest, I'd play (and have played) Diplomacy. Vastly better designed and balanced for MP games. Or Dominions 3 if we insist on only comparing to computer games, which is showing its age, but probably the best military MP game I've ever played (turn based and fantasy though it is).