The initial question was about "single point of failure". The answer is, don't create such a single point of failure in your life. And you regard someone doing that as "you must be either old or a hick". Maybe they're just someone who doesn't want a single point of failure for everything in their life.

For myself, I have a cell phone, but I don't have anything on it. No banking. No work apps. Nothing. When work asked me to put an authentication app on my phone so I could sign in using their new authentication scheme, I said, "No, I'm not putting any work app on my private phone. Hard no. Give me something else." So they gave me a little USB thingy to use instead.

If I lose my phone, I lose my contacts (but my carrier has a copy of those), my text history (but maybe my carrier has those too?), and any photos that I haven't copied off. That's it.