If our currencies and financial system were completely based off the value of gold and/or other precious metals where the amount on the planet is finite, wouldn't this eventually cause the opposite of inflation where the prices of goods and services go down as less and less gold is available as the population grows?
Wouldn't that also mean that wealth inequality and hoarding of gold make things even cheaper as less and less can afford to buy/sell at higher prices?
The real problem isn't the amount of money in the system, it's the amount of useful work being done, and the way the gains from that work are distributed throughout the economy. The ideal is a virtuous circle where distributed gains create more activity which creates more opportunity and invention which creates more gains.
The current system is based on control of the money supply, and is the opposite of that. Effectively it's just the Gold Standard without the gold. It leads to the same kind of hoarding and rent-seeking, both of which are economically destructive.
Nixon had to either devalue the dollar or completely default, and he chose to default and abandon fractional reserve banking altogether (though at the time promised it was only a temporary suspension of gold redemptions).