[Belac]

Keeping one's word is different from being a carebear. In Diplomacy, there is no research, no recruiting, no site-searching, and thus no reason to turtle; furthermore, there is no randomness or scripting in combat, so the only way to get a combat advantage is through surprise. In Dominions, you can spend long periods of time fighting no one, then declare war on someone and win. In Diplomacy, that would never happen.

Nevertheless, in Diplomacy there is still value to keeping one's word most of the time. Someone who regularly broke agreements in Diplomacy without any real benefit to them would swiftly develop a bad reputation. "Why did you stab me? You didn't get any useful benefit from it" is a valid reason to dislike someone, even when "Why did you stab me? We had an agreement" is not.