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.
You've basically supported the argument you were attempting to refute. If expenditure is required to ensure honesty then the expenditure is required to derive the value, because otherwise it will be cheated out of existence. You can't wish away the honesty part. Cheaters exist.
I'm refuting the notion that there exists some causal relationship between expenditure and value. That relationship is correlation in some cases, but not causation. Plenty of coins have been mined with great expenditure of resources yet are worthless now. The inverse is also true. Some coins have been mined quickly and without much expenditure, but are highly valued.