None of your examples are unique to social networks. There are many ways to keep in touch with people and many ways to gather information. These methods are usually superior in most respects too. What social media, like facebook, does do, though, is bundle it all together. It's like a supermarket.

But it goes beyond just being a supermarket. It has a unique selling point: the ability to signal. In my experience, the number of people who use social networks merely as email/news/entertainment replacements without succumbing to status signalling is very small.