Just as with fast food that depends on subsidized corn, ignorance and fossil fuels, social networks like Facebook represents the industrialization of our social interactions: fast, cheap, shallow and designed for mass consumption. And make no mistake, just like how the food demand is inelastic because our stomach doesn't grow bigger, so is our attention span as there are only 24 hours in a day, so the same strategies are employed by both sides, with Facebook being the new TV (how ironic, almost as ironic as organic food being industrialized).
And going back to the potato, we Europeans may have started eating it only 500 years ago, but the potato has been domesticated 7,000 to 10,000 years ago in South America. We simply discovered what other people have been eating for thousands of years. No such thing happened with social networks. Or with present day processed foods for that matter.
And you know, industrialized food and the modern lifestyle has been making us obese and gave us diabetes. We might also discover that this modern lifestyle is also bringing with it other gifts, like autism and I wouldn't be surprised at all if some conditions from the autistic spectrum are also caused by humans having shallower social interactions.
- broadcast but pull (not push) communication; everyone (from the group that can see a particular post) can join or leave a discussion at any time, and reading it does not require commitment to active participation
- asynchronous communication; I can drop a comment and read replies at my own schedule, and there is no expectation for immediate response
And no, you can't really disconnect it from the other side of social networking, i.e. posting cat pictures and news articles - they provide a social object, around which a discussion can form[0].
Complaining about social networks as "inferior" form of social interaction seems like complaining about potatoes as inferior food because they weren't around in Europe 500 years ago. Yes, living only on potatoes isn't the healthiest thing, but they are a decent food and even if you make it the core of your diet, you won't get sick.
[0] - http://gapingvoid.com/blog/2007/12/31/social-objects-for-beg... curiously, this text now starts with an image that wasn't there last time I read it, and that perfectly sums up my opinion on advertising