There was no reason that I could see. One guild member made a couple of jokes containing the phrase "your mom" over the alliance chat. No cursing or offensive content was included. That entire guild was then booted, to the tune of around 800K faction for the alliance. Then, other people pointed out that this was ridiculous, and then they too were booted from the alliance. Other guilds in the alliance, upon hearing what happened, left on their own. That is what happened. It should be pointed out that the reason the alliance does not hold Cavalon is the direct result of the removal of these guilds and their faction.