Are you sure all the people in your address book are as careless about that data? The friend with the restraining out against their ex? The minor celebrity with the unlisted phone number?
Are you happy with the possibility that a connection between you and someone else might be implied without being true? What if a known drug dealer* had your phone number in their address book? (Perhaps via a room mate or child using the landline to have called them once? Or through reuse of an expired disposable cellphone number?)
* or child pornographer, or political dissident, or terrorist, or…
Are you sure all the people in your address book are as careless about that data? The friend with the restraining out against their ex? The minor celebrity with the unlisted phone number?
Are you happy with the possibility that a connection between you and someone else might be implied without being true? What if a known drug dealer* had your phone number in their address book? (Perhaps via a room mate or child using the landline to have called them once? Or through reuse of an expired disposable cellphone number?)
* or child pornographer, or political dissident, or terrorist, or…