This is where I expect relays will also need to be involved - whether to forward certain messages or not. And from there whether accept / reject responses on certain notes.
Discussion
Clients should eventually be smart enough to look at the public blocklist of Alice and not render notes from Bob if Alice blocks Bob.
Yes, but I am also certain this behavior of sending all of the messages to all of the network will not persist long term. Relays will eventually start filtering... refusing to route or provide information.
I don't see that this can be exclusively done on clients also because users will not use clients that limit them.
