Before Facebook had an algorithm you'd see peoples posts in chronological order. The moment they altered that was where they began to influence behavior.
I do think that facebook is in the position to do something about its negative influence. And taking no action or saying "it's too hard to fix" is basically being complicit. You don't get to profit off of this machine without being responsible for its negative externalities. At least from a moral standpoint.
The solution? Stop the manipulation of what users see based on machine learning. Users should see what their friends and groups post chronologically. What would be the downside of that? I'd spend less time on facebook (an upside if you ask me) and facebook would make less money.