I think the other half is the more important one: to have a successful community, you need to be willing to be arbitrary and unfair, because you need to kick out some people and cannot afford to wait for a watertight justification before you do.
The best ruler for a community is an uncorruptible, bias-free, dictator. All you need to do to implement this is to find an uncorruptible, bias-free dictator. Then you don't need a watertight justification because those are used to avoid corruption and bias and you know you don't have any of that anyway.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
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