Case in point... how many phone numbers do you currently know, compared to the past?
Ha, that’s exactly one example that comes up in this household regularly.
I use a phone rarely so even if the technology for the phone number storage didn’t exist, I would still have trouble remembering important numbers. Of course as a teenager I had quite a phone book in my head.
I have key numbers written down in real notebooks. Same with the rest of the family. Dead/lost/stolen phone and there go the numbers of everyone you know.
Unfortunately for the-gadget-is-my-memory folks, even the most basic, utilitarian knowledge will go dead with the phone. That’s zombie apocalypse talk right there!