YES, these behaviors must arise in any group of thinking beings.
No, this is not like what happened before.
The Internet and social media dramatically accelerate the creation of new groups and the rate of polarization.
On the forums I am on, I have seen tiny social cracks become ongoing flame wars in the span of a few months. These are fringe opinions, with strong emotional components, become battle lines.
But worst of all, it is that the underlying issue loses all hope of ever being discussed peacefully or maturely.
A valid fringe issue, which would eventually have its day in the Sun, is now a point to test identity
These became issues, when earlier it was solved by the slower pace of conversation and discussion. Things are getting inflamed due to the medium. IT carries little nuance or context, and it amplifies the most acerbic and attention grabbing messages.
It makes things worse in a way human beings and cable companies alone could not.
My fear is all the leaders of the US and Europe who remember the horrors of the first half of the twentieth century are dead. And the power of divisive tribal politics is too tempting to the new generation.
Social media just makes those divides more readily apparent because people now have instant access to those they harshly disagree with. There's also a large amount of issues stemming from rational ignorance due to the sheer amount of data people are being bombarded with, and it's easy to often slip things past people's various filters depending on how you target them and their education levels.