In other words...we all agree that price fixing leads to either shortages or surpluses..but we all agree that fixing the price of money in a central bank is the right way to go. And we are not able to see the contradiction therein.
In the end it's a question of alternative mechanisms. Either we use the current system or we go with a "backed" medium of exchange. The "backed" version suffers from elasticity (but that may or may not be a good thing). So the issue becomes what are some other alternatives that aren't just derivative of the first two?