I don't like Facebook more than anyone else, but at this point aren't we just blaming them for enabling communication? By all means, criticize Facebook for privacy issues, but not for stuff like this, unless you actually want censorship on the largest scale ever in history.
I think it is fair to criticize unedited internet communication in general, as we have just recently learned that this form of communication did not result in the improvement of public discourse that everyone might have hoped. Facebook just happens to be the largest platform offering that. I don't think it is fair to consider large-scale censorship as the only other alternative. Having some kind of neutral editorial…
If the internet is meant to be a platform on which people can express themselves freely (and I believe it is) then unsubstantiated and hateful opinions are a given, not a sign that the internet has failed, but that it's succeeded.
What failed is the naive, idealist expectation that the internet would raise the level of intellectual and cultural awareness of the planet, but I don't think many people really believed in that to begin with.