It's about the best thing you could do for relayed events.. the scenario of not everyone adopting the technique and then accounts that are compromised have a clear runway to cleanly hijack the account into one you don't still have the key to.. doesn't seem a ton better.
This is why having something external to Nostr, or external to the events seems like the way. We already sort of push for that anyway with GPG right (and on nostr), by saying, here's my pubkey, it's on my GitHub/Twitter.. and etc.
This is also why I really kind of like the NIP05, but only if you control the domain.. maybe something similar to nip05 but without having to own a domain, like a message on the blockchain saying "here are my next 5 accounts"