The growth would have happened anyway. The economic system is just a way to trade wealth and keep score. It doesnt matter if it is fiat currency, gold or grains of sand that are traded. Being on a fiat system allows an outside player to siphon value out of the economy for their own gain the same as a tax. If we had been on a gold standard during this amazing growth period the only way an outside party could siphon off wealth is with taxes.

If we were on a gold standard and the government took 2% of every single transaction for the last 90 years we would still be better off. Inflation is a tax that is compounded over time.