Not the parent, but I agree with them: Many tech savvy people abandoned contact books decades ago. Contact books serve two needs - long term storage and quick reference to frequently used numbers. Computers have provided the long term storage, and various other facilities provided the quick reference, even before smart phones: human memory, print outs, sticky notes, pdas, basic cell phones.

In the 90s I knew people who'd set their browser homepage to a 'quick reference info' page on their server which included frequently needed numbers.

The only tech savvy people I've known to use contact books in the last twenty years seemed a bit eccentric to me.

My parents had a contact book when I was little (back in the 80s), but they eventually went to a system of cards standing up in a tray separated by last letter. It made it easy to pull it out when you wanted to make a call. They now have a mixed system where their most used phone numbers are in their iPhone contacts, but they have still have that tray for everybody else.

I had a contacts section in my DayTimer back in the 90s, but I've used a contacts program ever since I switched to using a computer-based calendar.