I'm not sure I understand your suggestion. Are you saying that someone should be able to sing a particular note, with no other frame of reference? That's a fun parlor trick, but doesn't really benefit you when it comes to singing actual songs (where the pitch is all relative).
No, I think he means using the tuner to tell how well you sing intervals, etc. Find a center pitch, sing relative to that and keep track of how off you go from the correct notes.
