As a side note, it might be useful for NIP-56 reports and NIP-32 labels to be able to provably associate an e tag with a pubkey by providing the signature from the offending event.

NIP-56 requires a p tag for the event author, but the report author could have lied about the pubkey unless you fetch the (potentially illegal) event. But with (pubkey, event id, signature) you can be sure of authorship without ever fetching it.

(A side-side note: why does NIP-56 even exist separately from NIP-32? It seems like just a special case of NIP-32?)