Assume Facebook no longer exists tomorrow. The same incentives that drive Facebook's behavior, i.e. human consumption patterns, will still exist. And will be exploited by another company. Facebook is merely one instance of a problem deeply rooted in humans.

Sure, there is the anti-competitive aspect to it. But wrt to the divisiveness and polarization, the exploitation by political actors, it would not make a difference. Something else would just rise up to fill that void. It's the digital equivalent of junk food. Banning Coke, would do nothing to solve obesity.