when I took away his iPad he was totally and utterly lost
That's sad enough to be tragic. Much the same with the electronic calculator crowd who couldn't run a mental sum if their lives depended on it. I can only hope that more instructors (and examiners) do the same sort of thing as you did. It wouldn't take long for the message to get around the Industry.
Another one which saddens me is the steam driven whizz wheel. OK, pilots can use the electronic version. However, the examiner still requires a display of some sort of competence to pass the various pilot exams. Being involved with theory training, these days, I have seen so many who have utterly no idea of why they are doing what they thought they had learnt (parrot fashion) correctly. I even had one supposedly university level class in recent times where several of them complained vigorously and bitterly when I presented some basic math background as to why you did this and that with the wheel.
One can only wonder where it might end ?