To be frank many people don't remember phone numbers these days, and just enter them into their phone-books to use. I know as a kid decades ago it took me a while to learn my home phone number. Sure a refresher index card could be used but that just isn't the norm.
I think it probably makes sense to give up. After all, we fought World War 2 without computers or cell phones, but people were different in those days. Now we take care of people more and prioritize how to stay in touch with caretakers, so we have to allow kids to bring their smartphones into the classroom.
