Are you saying battle is necessary because it is about "economy." Can you expand?
It's about linking economy with progression.
Your progression might be along the lines of "kill the warlock". The GM determines that the Warlock is level 10 or whatever and you need to get 9 levels worth of experience and loot (potions, gear, wands) to get that. Those levels and loot are your "economy" and your "progression".
The convenient way is combat. How else can you get that much loot? How else do you get that much experience and items? You go into caves, kill evil things, and take their moneys.
You can probably make a similar route like robbing houses or working jobs, but who plays a RPG to work at the blacksmith? Harvest Moon is one rare exception of both progression and economics working without combat.
The more I think about this, the more I feel it'd make for a great competition. Who can make a RPG good without any classical monster combat?