Sanger's Law is an observation, made by Larry Sanger circa 2005, I suspect that the cultures of online communities generally are established pretty quickly and then very resistant to change, because they are self-selecting; that was certainly the case with Wikipedia, anyway. Online communities' cultures generally are established quickly and then become very resistant to change, because they are self-selecting. Those users who are attracted to the existing culture join and help reinforce that culture. Those users who are repelled by the culture leave and no longer directly influence the site. This is especially true on mobocratic sites such as Wikipedia or RationalWiki whose policies and leaders are chosen by the community rather than by a site owner or a corporate or nonprofit CEO and its staff.
RationalWiki deleted this because it is not accepted as a law and Proxima Centauri (talk) does not know if it is attributable to Larry Sanger. Despite this the article seems to make a reasonable point.
http://features.slashdot.org/story/05/04/18/164213/the-early-history-of-nupedia-and-wikipedia-a-memoir The Early History of Nupedia and Wikipedia: A Memoir author, Sanger, Larry Adapted from a deleted RationalWiki article