Why? It is not as efficient. I can buy everything from stores but I use amazon, same thing. I don't actually use facebook though because I don't care about anyone really but for people that care, it is a solid platform.
There is a gap between "I want to know what people I know are up to" and "I want to meet with those people one by one to see what they are up to". Some people just want to passively watch and that is ok.
