Social media mobs are not the the root problem that we should be concerned with. They are just a byproduct of a bigger issue which is control of the major media outlets by big corporations.

It is in their best interest to polarize the society, ideally along some bullshit problem or identity (e.g. men vs women, old vs young, white vs non-white). This way people can release their anger and waste their time on pointless discussions (while consuming ads) instead of realizing the system is rigged and they are actually being screwed by the wealthy oligarchs.