The central banks of Austria, Bolivia, Brazil, China, France, Germany, Greece, Hungary, Peru, Poland, Venezuela, and Zimbabwe have all failed to stop hyperinflation.
You're conflating the ability to do something with actually doing that something. Also, what's your point with regards to inflation and fiat currency? That seems tangential to the parent comment.
The conflation is appropriate as the original clam is that fiat currency is backed by trust that the nation won't default. If the nation defaults in both cases, they are equivalent.
> The central banks of Austria, Bolivia, Brazil, China, France, Germany, Greece, Hungary, Peru, Poland, Venezuela, and Zimbabwe have all failed to stop hyperinflation.
Which of those were central banks of nations where debts including both private and public debt were denominated principally in fiat whose monetary policy was controlled by the central bank?
Some of them were pre-fiat (gold standard), and some were dealing with situations were obligations were largely in externally-controlled fiat (e.g., USD.)
Hyperinflation is caused by very limited supply. If there is not enough food around people will give everything for it. It doesn't matter what the currency is and how much you print or not.
What could the central bank of zimbabwe have done to stop inflation? I agree that central banks can almost always stop inflation...as long as they are controlling a reserve currency that actually has international value. Otherwise there is actually very little a central bank can do when your currency isn't used for imports, exports, international trade etc and foreign dollars/euros/RNB are needed to do almost any economical meaningful transaction.
They could have stopped flooding the country with Zimbabwean dollars and hyperinflation would have stopped immediately. Of course, the central bank of Zimbabwe was never independent from the government, but that doesn't change the fact that whoever was in charge of the monetary policy could have stopped hyperinflation at any time, had they wanted to.