It's not about the 90% difficulty... The difficulty is set to Normal, which is indicated by the Rook icon. As for the 200% difficulty, it's a matter of personal preference. What I find appealing in Heroes is the gameplay, but what's the point of 200% difficulty? Is it just about a prolonged start with zero resources? I'm not sure if that's enjoyable...
I myself played a year ago, mostly duels, 1v1, on random maps, without water or diplomacy, specifically on Normal difficulty.
Maybe it's fun to play against the computer and give it a handicap, starting with zero resources.