I think you have to look at it the other way. Facebook is a media company, just like NBC or Time Warner or Disney. However, unlike those companies, they've hit on a goldmine - they don't have to spend a dime creating content, their users create the content. This becomes an issue only when the users start making content that pisses off other users. Traditional media companies deal with this by, for example, firing directors or actors or cancelling projects. Facebook is basically doing the same, they're getting rid of content that messes with the only thing they care about - number of users times frequency of visit.
My point isn't political, it's to note that thinking of Facebook as anything remotely similar to a public square is a bit naive. It's Disney, they publish media, they just found a way to hack the business model so they get the media for free.
My political comment is that we (Americans) really do need a better public square, now that no one actually goes to a public square anymore and instead spends that time staring at their phones.