"There is Only One President at a Time"

Does anyone remember a president-elect forced to say that on a regular basis? Does anyone remember a transition period where people looked again and again to the incoming president for input and answers instead of the serving president?

Can there be any doubt that if someone proposed a constitutional amendment to transfer power to the president-elect now it would speed through the system and be enacted faster than you can say "there is only one president at a time?" And at some level isn't that just sad as all get out.