If you use and share a new nsec you cannot control who has the nsec, it can be shared infinitely, on the other hand by using this relay no one knows the nsec and still be able to publish with it. At least type 1 and 30023 as it is limited now. I am the only one now able to change the profile metadata and publish other kinds with it. 

 Did  @brito mean something like a "Post Anonymously" button in a Nostr client, which generates a new nsec?