Despite the link-bait title, he doesn't seem to want to make a definitive statement.
If you brought your gold to different people, they might all quote you different amounts, based on how easily the merchant or exchanger could convert the gold into their own currency.
That doesn't mean the currency itself failed, just means it was abandoned by those seeking to implement monetary policy.
It would be like saying P2P networking failed because vendors prefer the iTunes model.
It wasn't a gold-currency world, it was a world of gold-backed US dollar. It makes a huge difference. While the advantages of being a reserve currency superceded the disadvantages of not having monetary control, Bretton-Woods stood. Once the tables turned, the US ended the gold backing.
Bretton Woods stood for close to 40yrs. The current system has about the same age and much as Bretton Woods is failing because the US abused its position as reserve currency to wage war financed by debt. History does repeat itself, in slightly different color tones...
The point is that it failed as a currency as soon as it lost the government's backing.