Transparent filters are super important for a platform I think. Does your API include information about where someone might find the notes of blocked people? It's kind of pointless I think to say "we blocked @Joe_Shmo for posting spam" if people don't have a way to actually go retrieve those notes to verify you aren't intentionally or accidentally miscategorizing notes. Also, is your API part of the Nostr protocol? It would be awesome to eventually have it built into clients. Right now, new users are greeted with a huge wall of relays with no good way to distinguish them or guaruntee they are getting the notes they think they are.