Why do all "social networks" have to be a feed of news? Couldn't anyone think of anything better than a system in which people are only encouraged to talk about themselves and try to get other people's approval? In which having more "friends" is always better, because you have more potential for self-agrandissement in your narcissistic posts?
The social aspect is important though because in this architecture what you see is determined by who you follow (and who they follow, etc.)