I took a different interpretation of the word when I made my point.  I think we all just have different ideas as to what it means

1) Not allowing the 'bad person' to see your posts (part of Twitter blocking) - this is what I thought was not useful.
2) Not allowing the 'bad person' to participate in your conversation -- this I think is needed and useful. 

 thx for the clarification! 

 1) is not even possible for public nostr notes.. unless a client decides to enforce it, in which case one could switch clients :)
2) agree this is useful