Today's sociology lesson: In-groups and out-groups taken from some old textbooks
http://web.missouri.edu/~hartmanj/rs150/inoutgroup.html
hehehe. Seriously though, that's all this is. You have people identifying with certain groups (delta, Fi, democrat, aristocrat, etc.) and distinguishing themselves on that basis as different and implying a cohesion that just doesn't exist. All people bind themselves to certain groups and separate themselves from others even if it is in a very loose way. I've even seen people on this forum change their typing and from that change their relations to other people.
For example, someone starts typing themself as Fi and suddenly only they and other Fi types really value and understand intimacy. They start thinking that Fe types just don't get it in the same way, and refuse to see reality because they've created this distinction in their mind. They then create these bonds with other people in their Fi in-group and separate themselves further from the Fe out-group. It's based on something that isn't even true, yet becomes true in their minds.