Gold backed notes do not cause any wear on the gold. And we can use silver and gold for coin. Sorry Charlie, next time don't make a fool's argument and claim it comes from someone else's mouth.
Statement of fact is not an argument.
Examination of the use of gold throughout history easily will verify the truth of the wear on gold coins. There were also the deliberate methods of clipping, washing and otherwise diminishing the gold content of coins.
Sorry if the truth bothers you.
Gold-backed notes must be convertible into gold or it is not gold-backed. Then there are the hoarders who will keep all the gold they can.
Gold will never be a monetary instrument again.