For all the naive and idealistic dreams of the so-called “marketplace of ideas,” the first generation of large social networks has proven mostly unprepared and ill-equipped to deal with the resulting culture wars. Until they have some real substantial ideas and incentives to take on the costly task of mediating between strangers who disagree with each other, they’re better off sorting those people apart. The only types of people who enjoy being thrown into a gladiatorial online arena together with those they disagree with seem to be trolls, who benefit asymmetrically from the resultant violence.
This seems to contradict what has been said about Facebook exploiting users's attraction to divisiveness and polarization. See [1] and [2].