The USD (and more importantly, the banking system), also allows for efficient high-volume transfers, reversibility, ID verification, and fraud investigation. None of this is possible with blockchain, by design.
I'd argue that USD in isolation doesn't support those use cases: the banking system does.
There is no reason a parallel banking system with all of the same features cannot built with Bitcoin being used as the denomination. I think this future is increasing likely (probably much to the chagrin of decentralization advocates) as Bitcoin increases in value and number of holders.
efficient high-volume transfers - risky and expensive to do with cash, really requires a hawala-like middleman (often a bank)
reversibility - not true of cash, only true within the context of softer credit systems. You could build a "Venmo backed by Bitcoin" where funds cannot be withdrawn for the reversibility period if you thought there was market demand for it.
ID verification - subject to discretion of counterparty
fraud investigation - Bitcoin is likely much better than USD for this because of it's traceability.
Which is a case that made headlines because of how unusual it is for this money to not get returned - it relies on an ultra-specific set of circumstances and still could have been decided the other way.
