If they'd called the bank the next day, the bank would certainly have reversed the transaction. If they'd made a fat finger error on the blockchain, there would be no one to call. It's entirely possible for a fat finger error to send $10M to a nonexistant blockchain address, so you can't even work it out with your counterparty; the money has been destroyed (assuming the network is secure in the first place).
If you think this is how money should work, or how a certain settlement layer should work with reversals implemented in a higher layer, fine. But this incident is certainly not a counterexample to this argument.
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This was a fat-fingered fiat refund. They only realized 7 months later. What was that about banks saving people from stuff like this?
If they'd called the bank the next day, the bank would certainly have reversed the transaction. If they'd made a fat finger error on the blockchain, there would be no one to call. It's entirely possible for a fat finger error to send $10M to a nonexistant blockchain address, so you can't even work it out with your counterparty; the money has been destroyed (assuming the network is secure in the first place).
If you think this is how money should work, or how a certain settlement layer should work with reversals implemented in a higher layer, fine. But this incident is certainly not a counterexample to this argument.