They aren't mutually exclusive. Lots of games have traditional scoring systems and also achievements.
Fame is our real achievement system. If we displayed Fame more prominently and listed the individual accomplishments that led to each point, we'd see more people chasing their cheevos.
But the ways of earning fame are not devised to encourage war, are they?
Also, when giving bonuses to one realm, you're basically still punishing the realm not going to war. A problem with TMP was that it kept weak realms weak, where would that suggestion address that issue? The idea that realms would join in on wars for future gain, turned out not to work in-game.
