Sure, but they could simply prove that the USD is backed by trillions of dollars of USD-denominated debt and tax bills which other people need to meet obligations. The confidence that implies is significantly different from the confidence implied in "number went up after going down last year"

Why does everyone get so hung up on the gold standard? What intrinsic value does gold have? 8% mined each year goes to technology and industrial use cases, that has value, and most importantly creates more value. The rest is people saying "Oh shiny", which has a less real connection than a paper note where obligations are traded and met.

The USD is backed by 11 nuclear aircraft carriers, 68+ nuclear submarines, 8725+ tanks, 1,359,685+ military service members, a police force and one IRS that makes damn sure taxes are paid in USD or "damn would be a shame if the governemnt took your home/car/freedom away"