Or as I put it when I started this board...
"Rule 1: This isn't a dumbocracy. It's a managed conversation space. You are not free to pollute this board with word garbage. The conversation is subject to a set of rules interpreted by a board manager (aka censor). See above for rationale. If you think you have a right to say what you wish in a rule-framed setting, read the introduction again. Freedom from tiresome and obnoxious commentary makes a richer and more friendly space for others. Wild, unsupported assertions waste everyone's time. There's no obligation for me to have to put up with you if you peddle nonsense. On the other hand, I welcome thoughtful posts regardless of whether I agree with them. There's plenty of other space online for you to post if you just wish to vomit letters some place. If you make yourself unmanageable, I will remove you. Before blaming me for it, use a mirror."
In the end, what happens in social media spaces is that communities develop in isolation. This is true precisely because people don't communicate in a polite and friendly way on a large scale. There is no idealistic market square. There are pragmatic conversational bubbles.