As a die hard observer [when I went to Mardi Gras parades, I usually spent my time watching the people who were watching the parade] of people [as opposed to being in the process; I'm sad that way] I find MMO guilds fascinating.* Something like an office, except most of the people in a guild choose to be together, for widely varying reasons. You have nearly every sort of personality there is; nerds, leaders, wannabe leaders, kids [real and the adults-who-never-grew-up], alcoholics and junkies, mentally ill [those on their meds and those who are not], normal people [whatever that means these days], and just plain nuts. If you have frequented any kind of internet forum or chat room, you know exactly what I mean.
So you take a mix of all the strange and not-so-strange people who congregate on the internet and put them in the same room, so to speak. And the kicker is that I am part of the stew. I'm not the spoon, or the beef, just a carrot or potato, but I am in there. So I see what is going on, and am still affected by it. A large percentage of the posts in any WoW forum concern guild issues. Our internet "connections" seem to take a larger emotional toll than those who don't frequent the 'net might believe.
I am sure a study of the life cycle of guilds/clans in MMO's would be fascinating to read, at least for those of us who play.
* I apologize for the horrendous, digressive structure of this sentence.