You've attacked what could interchangeably be dollar or gold asking what it might buy or store, failing to recognize I was measuring relative stability rather than absolute stability.

The dollar has lost over 95% of its value since inception of the federal reserve (at which time dollars nature changed significantly) in 1913 against some imperfect measures of CPI. That gives you a 20x difference over time, downward. Gold has not perform nearly that bad at price stability.

We could go back further than that when the dollar was a lot more stable... but at that time dollar was backed by gold and there wasn't (mostly) a central bank nor gold possession bans that let them mess with the price quite in the same way they did later.