Factions (part deux)

Why?
I'm used to road versus dirt, racer versus rider, people who are "training" sneering at people who are commuting... Used to it, but I still don't understand it. We all ride bicycles, we love our bicycles; why do we hold such animosity for those who worship a different style?
And now, as I explore deeper levels of our addiction, I find deeper animosity. Fixie riders who sneer at other fixie riders; ninjas who are too cool to be seen with the cruisers, students in one school who won't ride with students from another school, label-whores who won't stoop to be seen with anyone "generic"...
Why?
A thousand years ago, when I began riding, all that mattered was two wheels. Oh sure, the Stingrays got the style points, but they didn't hold up to the Western Flyers and Jet Pilots. Those 26"-wheeled behemoths could survive anything, even being t-boned by a '60s Cadillac (personal experience). But we never divided into factions, we just rode. Every kid in the neighborhood from 6 to 16 that had a bike would be out in force, doing crits around the 'hood, blasting through vacant lots, roosting off every piece of transition we found. We all had bikes, we all loved our bikes. Eventually some of us "grew up", and bikes (as well as the semi-religious experience of riding them) faded into memory. If they returned, it was not to the fold, but into a boutique-based self styling that harkened the factionalism we have today.
Why?
Roots, people, remember your roots. Diamond frame, cranks, chain, two wheels. The most efficient machine ever invented. No matter how technologically advanced the components become, it still boils down to a bicycle. The basis of it all.