@jonny @jeremy that's interesting because the earlier online communities such as Usenet were well known for communicating norms to new contributors (until AOL and the Eternal September) and the communities grew strongly with those norms.
I wonder if the wikis with the greatest longevity also had the strongest community practice? I can certainly see some fandoms being particularly drawn to written rules, and new contributors welcoming a RTFM approach to joining, whereas others are very "don't tell me what to do". And the former have tended to last longer than the latter, even when they fight.