Comment by canucker2016

"...but no social network AFAIK has a "go off on a tangent" action (which would give you a message composer for a new top-level post, pre-filled with a cited quote of the post you were just looking at, but without your post being linked to that post on the response-tree level.) ... "

On Usenet, if you were altering the general SUBJECT of a post, you'd reply to a comment BY PREPENDING the NEW TITLE/SUMMARY of your post to the PREVIOUS TITLE of the post to indicate that you HAD changed the GENERAL SUBJECT of the post to something else AND end your NEW TITLE with "Was..." to prefix the previous title, e.g. "Hackintosh is Almost Dead" => "My Changing Hobby Habits Was: Hackintosh is Almost Dead"