Price is not a proxy
I was not talking about substitution. When I said "Price is not a proxy for production" I meant that higher prices do not necessarily mean production will rise, that low prices do not necessarily indicate a glut. Price is a function of supply AND demand, not just supply. But that's a separate topic from substitution. I don't see how you could have inferred any such prejudice on my part. I said what I meant and I meant what I said.