Cause we legitimately edit the news regularly, and after the 2 mins grace. For when we add quotations, or opponents, or match times, or Jamie's results, or if we put in audio or someone else edits the post to make it sound better. You could end up with 7 or 8 edit messages at the end of each news post, which looks a little unprofessional I think. And considering it's only staff that can edit in News I suppose it's not so necessary to know on that board.
I think you would only see the last person who edited, so that's one edit message regardless of how many times it was edited.