The argument that social media companies are more powerful than governments is fundamentally undermined if social media companies don't actually have any of the powers traditionally ascribed to governments (such as a monopoly on violence) and are, themselves, subject to the authority of governments.

Twitter banning Donald Trump's account doesn't make them more powerful than the US government, for instance. MacDonald's serves billions every day, but no one calls them a superpower.

The power to censor speech and control the spread of information is one of these traditional government powers and these companies routinely use it. In a democracy, control of information is as good if not better than an army. Installing a new government by force would get the international community pissed at you - the UN might even wag a finger at you angrily. Winning a democratic election because the people's beliefs were groomed by an algorithm in full control of which information they see and which they don't is something nobody will even know happened. Your government is as legitimate as any other and your power isn't much less absolute than any military dictatorship.

I'm not saying this will happen - it surely won't. But it could.

What will and already does happen is that companies won't replace governments with their puppets, but use their power over information to extract more and more value from the people and to get existing governments to make it easier for them.

Violence is a crude tool used by empires of the past. Even governments are starting to abandon it. Access to and control of information is the name of the game now. Governments need to hack, deceive and threaten to get information, but we've already voluntarily put these tech companies in control of ours. Governments have already lost on that front.