For your consideration ...
The quantity may change as such when new stock is added to the economy, (say after a large mine load discovery), there may be a small increase in prices of goods and services for a short period of time but then prices will stabilize.
That is the definition of losing (or gaining) value, if something can gain value it can certainly lose it.
I think you look at precious metal based currency through rose colored glasses. I'm neither for or against it, but I think you are basing your beliefs on one side of the argument entirely.
One benefit of inflation is for anyone or any entity with a mortgage, or any other long term debt. A fixed payment today may be significant, but down the road the payments are far less.
Another example would be a royalty, so I have to pay ACME corp $1 for every widget I sell, 20 years from now that $1 is a much smaller chunk of the pie.
You are confusing temporary price inflation with fiat monetary inflation which is permanent and ever increasing tied to the expansion of the fiat money supply.
Pre-1913. Gold's value did change, slightly, relative to the quantities of silver. If more silver was discovered, it increased the value of gold relative to the amount of silver. If silver supplies declined, the opposite. The ratio was first set at 15 ounces of silver to 1 ounce of gold, 15:1. However normalcy in prices returned after a new supplies were introduced into the economy. Today, that ratio, based on fiat currency spot prices, is about 90 ounces of silver to 1 ounce of gold, 90:1.
Your supposition that there is a benefit to inflation is the lie you've been told. Because, though yes, over the years, through the inflation mechanism, a mortgage will be paid with inflated, devalued, dollars, making it easier to pay that fixed mortgage. However, if the house went from $100,000 from 20 years ago, to now $400,000, it only represents what inflation has done. It is not because the house when up in value, it is because the dollar's value went down due to the increasing of the money supply. On top of that, over those years wages increased, but also the taxation that followed that taxed that increase which reduced what was made. As well as increase of property taxes based on the falsely inflated value of the property. *Monetary* Inflation is a losing proposition for everything and everyone. *Monetary* Inflation is theft. *Monetary* Inflation is a hidden tax because it devalues the dollars currently in one's possession. Forcing people to work longer to just keep up. and maintain their standard of living.
"I think you look at precious metal based currency through rose colored glasses." Nope. I just believe that The People should have control over their money system, as the US Constitution intended, rather than greedy private bankers which have no allegiance to this Nation. When the people have gold and silver coin in their possession, used as money, they control things. The govement just can't create money to use for stupid projects, because government cannot create gold or silver. And if the government went to the people for money for stupid projects, the people would say no, stopping the stupidity. While at present, under the current fiat money system, We The People have absolutely no say in the matter.