I make it a point to memorize the home numbers of people who are local. I do this so I have a large number of options in case I get into an accident and have to give out a number to a rescuer or get arrested and need to make that one phone call. Seriously, that's the kind of stuff I worry about.
But not many cell phone users are as neurotically prepared for these situations as I am. They can only remember the phone numbers they learned before they had cell phones. So when they lose or break their phone, they see the downside to their dependency. And many cell phone users are also guilty of not writing the numbers down as backup so they have to recreate their electronic address book from scratch. (I have to admit that I also write down all the numbers. I definitely worry way too much.)