You are assuming that Facebook is intrinsically negative, which is not always the case. It certainly has its pros and cons. For example, my parents use FB to find and connect with old friends from grade school. Some use it to know about local events. Some use it to promote their business or their fledgling indie band.
Aside from this, in my home country, the Philippines, SMS & telephone services are expensive. Being a 3rd world archipelago country, infrastructure in the provinces is so bad that cabled & optic internet is not available for a lot of people. Facebook is a gem in my country in that they provide free internet for anyone utilising FB's services with a smartphone (you can buy cheap 2nd hand android phones there for less than $20). The folks here use FB's services to keep themselves updated with the world as well as to call/chat. It's a great way to connect and recently people don't even memorise their phone numbers anymore and instead, people ask each other for their facebook.