All of the previous comments apply fully. The main reason to "censor" ourselves is simple common courtesy and respect for others.
For the most part there is very little need for moderation, most people simply do the right thing. However sometimes people do lose their tempers, often through some misinterpretation of someone else's statement which gets out of hand. This can lead to several outcomes. First, as has been mentioned, knowledgeable posters leave, never to return. This has been, in a few cases, a huge loss. We get over it, but still, a loss is a loss.
Beyond that, people
have threatened legal action. Never mind the disclaimers, it's been done. For me to hire a lawyer, even just long enough to have a case thrown out of court, could be prohibitively expensive.
Lastly, I've been threatened with physical violence against myself, my friends and family. In this case, no amount of self censorship would have made one iota of difference, but it does demonstrate the magnitude of some of the behind the scenes activity that occurs.
I really don't think a little respect is too much to ask for in return for free and open access to the NGDF. I enjoy the forum too, and I prefer to focus on those topics which interest me. When I have to spend hours focusing on a handful of posts about which I have no interest, I sometimes wonder why I bother. Fortunately that doesn't happen very often.
Don