That's good thinking, but again that should be at a client level, not the protocol level.  If a particular community want to develop an app based on the idea that they know best who their members should or should not see, they can build and maintain it.  We don't need and I don't think most of us would want to give up that control.

However, that does identify a need for private groups, where a specific set of people can speak freely on specific topics without being exposed to the rest of the world.  One of the biggest drivers of growth for Facebook and Twitter was the difference in how they handled privacy.  On Twitter, now X, everything is public.  But Facebook created private groups where people could organize and actually conduct business, making decisions with internal consensus rules or governance that worked for them.  This is a separate topic than Mute or Block, but it is a critical piece of how socialedia has evolved over the last few decades that Nostr needs to catch up with. Even X is trying communities, although they seem to be crap like everything else on there.