Facebook is a publisher
.. and as such should be subject to the same laws and legal liabilities as newspaper and book publishers.
Facebook will argue its current status as a common carrier is correct. But the telephone company does not listen to my calls and interrupt a conversation about barbecues with suggestions that I buy a new Weber. The fact that Facebook scans your posts and sells this data to advertisers should be enough to revoke its common carrier status and get it classified as a publisher which it so obviously is.