I think Tribalism is a normal default human behavior back in the days of Oral culture that was disrupted by the Gutenberg Printing Press and the sudden surge of Mass Literacy. This sparked an unusual amount of Individuality and Contempletive thought.
As a 'media experience' reading is a solitary and private experience between yourself and the content, reading at your pace, one line at a time, considering what is being said.
Compare this to say receiving a Facebook instant message or Phone Text. It's reading, but it pulls you into a group activity, and it involves you in the technology experience.
I guess to get to a point, I'm heavily influenced by Marshall Mcluhan on this topic who feels that the rise of the Electric Communication Age has pushed us forward technologically, but also causes us to slip backward socially. With that, I do think we're a patchwork now of Individualists amongst Tribal people. A smaller minority are Artists who try to interpret these trends and explain to society what we're becoming.
As these effects advance and influence our identity across the board, it can lead to a steady rise in Nostalgia which I think we've been seeing a lot of. I think the mid-80s was when this effect surged and interestingly that is the time period often tapped for entertainment like Stranger Things. We also see quite a few Remakes from that era or long delayed sequels like TRON Legacy or Blade Runner 2049.
Another aspect of Nostalgia is the return of older styles of clothing. I've also wondered if a combination of Tribalism and Nostalgia is why there seems to be a resurgance of Tattoos. It seems like I see awful tattoos everywhere.
I want to qualify some things mentioned in this clip. By "Violence" he doesn't always mean physical, but sometimes verbal or general abrasiveness.
Also, he's not saying people simply in a group hate eachother, but that the Electronic 'Global Village' brings people way to close together. It becomes something like angry relatives at Thanksgiving on a wide scale. Mcluhan also described this as an Ann Lander Column writ large.