I think of rudeness in LW discussions as a signal. Broadly speaking, LW commenters are rude when they think they are dealing with a stupid argument, and/or an argument that fails to follow the established rules of rationality. The implication is that they can't be bothered writing a more detached response, and (since rudeness is more likely to drive users off the site) that they would not want to see similar comments in the future.
It strikes me as a useful signal; sometimes more useful than karma points, which can be affected by factional or 'political' considerations. This might be one reason why Crocker's Rules tend to be relatively popular here at LessWrong.
Nonetheless, it might be worthwhile to try and challenge the social norm where users with more status can afford to be more rude. In my view, it would be interesting if some users with high rationality skills were willing to be expressly low status users, or "resident trolls". Their role would include debating with especially irrational, politically-motivated or trollish newcomers. Rudeness on their part would be expressly encouraged; due to their low status, it would hopefully not be seen as threatening the social standing of other LW users.
Ideally, users with the technical ability to delete comments here (most obviously Eliezer) would also take on the low-status, "resident troll" role. This would ensure that such technical measures are only used a last resort, if any attempts at discouraging unproductive commenters by social means failed.
Hmm. I'm not sure we want more monkeymind posts, which seems to be a desired goal of your proposed policy.
On LessWrong, we often get cross, and then rude, with each other. Sometimes, someone then observes this rudeness is counterproductive.
Is it?
As a general rule, emotional responses are winning strategies (at least for your genes). That's why you have those emotions.
Granted, insulting someone during your rebuttal of their argument makes it less likely that they will see your point. But it appears to be an effective tactic when carrying on an argument in public.
It's my impression that on LessWrong, a comment or a post written with a certain amount of disdain is more-likely to get voted up than a completely objective comment. A good way to obtain upvotes, if that is your goal, is to make other readers wish to identify with you and disassociate themselves from whomever you're arguing against. A great many up-voted comments, including some of my own, suggest, subtly or not subtly, with or without evidence, that the person being responded to is ignorant or stupid.
The correct amount of derision appears be slight, and to depend on status. Someone with more status should be more rude. Retaliations against rudeness may really be retaliations for an attempt to claim high status.
What's the optimal response if someone says something especially rude to you? Is a polite or a rude response to a rude comment more likely to be upvoted/downvoted? Not ideally, but in reality. I think, in general, when dealing with humans, responding to skillful rudeness, and especially humorous rudeness, with politeness, is a losing strategy.
My expectation is that rudeness is a better strategy for poor and unpopular arguments than for good or popular ones, because rudeness adds noise. The lower a comment's expected karma, the ruder it should be.
You jerk.