<snip>
Would they be useful? The lines change depending on window size, screen resolution, font size, etc. so they couldn't be used to tell another person which line a comment refers to.
<snip>
Are you sure about that? when you do a diff, it gives you a line number (at which the changes occurred there) but when you go to the article, you keep searching for it (at least what happens to me).. if there are line numbers, it would be easy, just scroll to the line...