As a people, we tend to group ourselves into tribes or communities that accept our foibles and issues and often reflect them. Perhaps no place is more representative of this fact than high school. Some of my favorite movies are about high school: Sixteen Candles, Fast Times at Ridgemont High, The Breakfast Club and so on. The reason: everything falls into simple, neat categories (jocks, stoners, beauty queens, nerds, etc) and the real action takes place when someone tries to stray outside the natural groupings (a jock becomes a stoner, for instance) or when two groups intersect (a beauty queen dates a nerd, for example).
In business, there are tribes or communities as well. You have finance types, marketing types and sales types, for example. These tribes are social among themselves, share the same language and experiences, and look at the other tribes or communities with suspicion or disdain. We have the Six Sigma types, the manufacturing types, the legal team and so on. And for the most part, we work in small, homogeneous teams with little intermixing.