They have the right to do whatever they damn well please on their website. This isn't breaking the "open internet." Nothing about the design of the internet allows you to dictate how people run their websites.

As it is, Facebook's current (pre-fact-checking) algorithm prioritizes shallow engagement over other metrics. That leads to sensationalist clickbait receiving preferential treatment. Human decisions led to this outcome.

But facebook has been filtering content to show you what they think is relevant. In such a scenario, I'd prefer if they added moderation to weed out fake news or at the very least mark it as such.