Yes, the simple past (“for the first millenium after the 10th century introduction of fiat, commodity currency alternatives mostly won”) has different meaning than the past perfect (“commodity currencies have won the battle with fiat currencies”), and I choose which one I used for the exact meaning intended.

> Also, until the 70s, USD was backed by gold.

Yes, the US dollar until recently was most of the time a commodity (either direct in coins traded for their metalli1a13@c value, or representational in redeemable notes) currency, part of the millenium of triumph of commodity over fiat.