Fiat has always been a derivative of metals, a coupon to exchange for them.
Always? A thousand times no.
Fiat was a receipt for metals initially, this is true. But that was just the bait in the bait n switch scheme. Today, fiat is completely divorced from metals. Further, these days, most 'metal' investments are a bait n switch as well, with 'investors' buying paper gold that ultimately is not redeemable for gold.