OK Dave, I think you might be right about the distinction between ball lines and putter lines, but it's unrelated to intent. When you make your stroke, the line on the putter has been removed (like your caddy pointing out the line for you before you putt), whereas the cheater ball line is still sitting there during the stroke, showing you the way. The putter line no longer indicates a line for putting once the player starts the stroke. Yes?
(Although I do tend to agree with JES that 8-2(b) seems on its face to be about placing marks on the putting surface, rather than on the ball or on equipment.)
John