People not being able to talk to one another is definitely a big part of it. Another thing to think about is how much the mediums of communication have changed since the PC era began.

I don't think people appreciate just how much communicating in a specific format begins to change the way you think and perceive the world. If you talk frequently in a medium limited to 140 characters, that will affect the way you think and set up communication. Same goes with pictures, or only video. The means by which we interact and shape the world also shape us at the same time. Are we that surprised then that an outrage and drama driven culture emerge from tools that are driven by instant emotional reactions?

Another thing to think about. With everyone having access to the ability to mass produce and distribute content to the world, what you consume begins to matter more and more. If all you want to eat is mental junk food, then you have all the mental junk food you could ever want for eternity. No one is going to stop you. No one at the internet companies want to stop you. People have never had to watch for this sort of thing before. Are we surprised that people binge on content that strengthens their world view and neglect views that challenge their own? There is no way a balanced view of the world can survive when people don't think about what they spend their time consuming and adjust.

There is a lot more going on. It's a multi-system problem that feeds into itself and other systems at the same time.