I'm a newbie to this site but I when I first joined online-communities some 30 years ago this thing was not called "internet".
It was a jungle for science-freaks and whenever you met someone from somewhere on your screen you were delighted and curious - and everybody were sisters and brothers in the brave new world we were allowed to spy in by the courtesy of the military.
Those days there was a "law" promoted by one of our most respected fellow-scientists (and believed by many others including myself): it said thet any online-community counting more than 500 members - an unbelievable crowd in those days - would for sure collabse within short time

Today I'm in professional forums counting over 30.000 members - and they work well

The recipe I believe is
1. the community is not primarily intended to stay anonymous but to physically meet in the "real world";
2. the common interest for information and exchange is overwhelming any short-time flaming;
3. the community is big enough to ignore personal feuds.
If those 3 criteria are true, you don't really need special rules as the "normal" rules of behaviour will be respected - and sufficient.
I don't read those "rules of engagement"-pages - and never ever had a problem. I just act as I would when meeting people in the "real world". There, I use a smile or a physical touch to send the message: "I don't mean no harm to you". In internet-forums I send a friendly icon

Allthough I'm an attorney by profession I believe applied common sense is by far superior to written rules

This forum works well - and if it should ever crash it will not be for the lack of written rules
