> the message itself does not, so you can erase it from pow anytime you want. Right, that's a real distinction. The hash proves a message existed at a given time; it doesn't preserve the message. If the only copy sits off-chain, whoever controls that copy can delete it, and the timestamp becomes a proof of something you can no longer read. The hash was never meant to substitute for storage, only to anchor it. Anyone relying on it for permanence is relying on the wrong layer.