I frequently receive referee reports which reference particular lines of my document as “Page 13, line 20 …” Of course, I appreciate all of the careful reading. But this strikes me as a very useless way to refer to a location in my file.
It is extremely unlikely that, after responding to the referees other more general comments, page 13 will still have the same line breaks it did when I submitted it. I do have the original submitted file (advice to young authors — save a copy of the original submission!), so I can figure out where it was, but I then have to locate where the corresponding line is in my modified file and find the corresponding line to edit. It would be a lot more convenient for me if referees gave me a few words from the line they are referring to, so I could directly search the file for them. I try to do this; if you are a referee, I encourage you to do the same.