No, it seems that you are the one that don't understand. A piece of paper is not Turing Complete because the computation happens in the head of whoever is hold

No, it seems that you are the one that don't understand. A piece of paper is not Turing Complete because the computation happens in the head of whoever is holding the pen. An excel sheet (or actually a power point presentation!) is, because the user just has to mindlessly, unconditionally, do a simple, non computational action to make the cycles go forward. There is a difference between the two scenario, and if you can't see it, please do ask questions until I'm able to make that clear to you.