People are stuck on the question of value, and come to the conclusion that value is derived from expenditure of resources. But that's simply not the case. Value is derived from utility. In other words, the question of value is related to usefulness, not expenditure.

Expenditure is required to help ensure honesty. If a reward requires resources, but cheating jeopardizes the reward, then the incentive is to be honest when expending those resources. That's the PoW model. This model has absolutely nothing to do with imparting value on a commodity. The utility of the commodity takes care of the value.