Not really, here all the notes would be published with the nsec/npub of the relay, if you generate new keys for every note all of them would be published by different identities. Application cases... I don't really know, may be some interesting use cases, for example you can set the nsec of your main account in the relay and all the notes would be signed with your identity, some kind of remote signer... Other for example may be some merge between nip 29 and lowent.xyz

gzuuus_

nostr

Mixer-relay, a relay that anonymizes your notes

Sounds like a good idea. Isn't that the same as generating new notes with new keys every time? I don't see a good application case!