i honestly have no idea what back end code would look like for a feature like this. The example i am aware of is from reddit, which builds off a feature to collapse a comment to >[-] Below down vote threshold (account name, points) What that does on the user end still load the page as normal, but hide the comment element to the above single line, and hide any responding comments below it. What the block user feature on reddit does is compare all comments to a block list for each user account, and collapse any users on the list after the page loads. after typing that out, i think i get a glimpse of how complicated it could be.