The intersect of supply and demand is necessarily the price equilibrium. Value is only equal to price if the buyer and seller both have equal information and neither is operating under any sort of constraints that force certain market behavior.
Your generality may often be true in certain contexts, but increasingly, one should operate under the assumption that the seller has a significant informational advantage over the buyer, and this advantage will be used to capture additional value.
Your generality may often be true in certain contexts, but increasingly, one should operate under the assumption that the seller has a significant informational advantage over the buyer, and this advantage will be used to capture additional value.