A deeper diagnosis is that any banking system with clawback/immutability is fundamentally going to have to be permissioned and somewhat closed. You have to know

A deeper diagnosis is that any banking system with clawback/immutability is fundamentally going to have to be permissioned and somewhat closed. You have to know who every participant is, and everyone has to be subject to a risk analysis. A fraud risk anywhere in the system is a fraud risk everywhere in the system. This leads to a huge amount of inefficiency and rampant anti-competitive business arrangements. We still pay ~3% fees on credit card payments (in the US) that haven't dropped in decades -- despite the fact that nearly every IT business has seen 99%+ cost decreases since the 1970s. There's nothing wrong with mutability as an idea. If people want to build closed and mutable systems with a clawback feature, they should be able to. But those closed systems should be built on top of an electronic funds transfer system, they shouldn't be built into it. Then there's a chance you might actually see some competition.