Why not? We have deleting already which is also a kind of editing
Discussion
Deleting does not work.
It's not possible for edit & delete to work properly, because relays can do anything they want. If they want to keep it, they can keep it. Actually there is already a NIP for replaceable events (editable), it's NIP-16. But editing & deleting are only a request to relay operators. No way to force relay operators to follow it. And you can't choose which relays your notes go to, because anyone can rebroadcast to any relay.
Oh, thank you for reminding me. I‘ll take a look at NIP-16. Although there is no perfect solution, I still hope that clients can support this function, which can solve some problems.
It's not up to the clients, it's up to the relay operators, and as I said, you can't choose which relays see your notes. Normal notes (kind 1) are not replaceable, so clients would all need to switch the note type in order to make normal notes editable (replaceable). Even if you replace them, relay operators can keep and display old versions.
Basically, you should consider that every note is permanent and can't ever be changed or deleted.