Here's one more bit of history that I scanned from another PI Newsletter, Volume 14 No.2 (1988) - but I don't want to get crossed up with the owner of this material....
When you block a person, they can no longer invite you to a private message or post to your profile wall. Replies and comments they make will be collapsed/hidden by default. Finally, you'll never receive email notifications about content they create or likes they designate for your content.
Note: if you proceed, you will no longer be following .