What's really scary is that you are averaging 4.2 posts per day over those four years and that does not even include posts from any of your other... ahem, "friends".
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 .