We clearly play different games. I do not know those but I know many others that do not include mainly the armys power to first place of the score but the population or buildings points. If feel you are overnumbered, then you should ask your allies to help you. Even then, you are not the only person who can win the world for your side (I do not know if you are from the dark side), you must cooperate and I do not think one player can easily outnumber armies of two players.
The important thing is, if you applied big penalty for having strong army, you could easily kill them by sending reinforcements to the abandoned villages or players who are going to end the game which are attacked by your enemies. Every strong player with big army usually farms a lot, so defending the villages he farms would be a great loss for him, if there was a big penalty. Of course, those abandoned villages have no walls, you have got no bashpoints for that. But at the end of the day he loses more than you because of the big penalty. Do you get my point?