I'd argue that cryptocurrency payments to anonymous receivers should not be irrevocable. If you want to send money anonymously, that's OK. But, to prevent fraud, receivers must be either known, or subject to clawback.

That could be done with a smart contract. When you buy something with a cryptocurrency, the funds go into lockup for, say, 30 days. With no action by either party, funds are released to the seller after 30 days. If the buyer wants to dispute the transaction, they can trigger an arbitration hold by sending a message to the smart contract. The seller can then give up anonymity and go to arbitration or court, or abandon the transaction.