Oddbean new post about login | logout number one there is no proof of time in nostr so you could back date an edit do i need to say more?
The x tag contains the file hash, you don't need the time attestation to spot a remote update.
note hash, good point but delete already covers this use case edits are good especially as reactions and can be expanded to others doing them, annotations etc, the issues of edits are really a ui problem not the note schema