Effects of slavery as a way of organizing the economy? Everybody knows slavery is bad, end of story, which tends to cut short any analysis of its effect on internal efficiency, productivity, etc.
Who calls "Crocker's rules"? The guy who wants to start the discussion about the economics of slavery? The guy who thinks it's viable? The guy who thinks it isn't viable and anyone who thinks so should be shot? How does it work?
Furthermore, what's the point? I mean, if you're in a discussion group where there's a non-zero probability that one of it's members will pick slavery (or something else equally apalling) as a discussion issue, but group members are self-selected (which is a reasonable supposition for groups in general, and even more so for obscure mailing lists) then it's likely that all members are amoral enough for discussion purposes such that this "Crocker's rules" thing would be redundant.
The article explains you can only declare Crocker's rule on yourself, and can not force it onto others who have not accepted it. A discussion will only work under Crocker's rules only if everyone consents.
What I meant is that I find it unlikely that in such a group there would even be a strong moral reaction to any issue in the first place. I don't know about the extropian mailing list, but take LessWrong members, for instance. They are quite shameless about the topics they choose. And they're not much given to non-cognitive criticism either (e.g. calling someone an ass). So calling on "Crocker's rules" would be just redundant.
What is the point of ignoring something that doesn't happen?
Edit: On the other hand, it relies on the assumption that there's a trade-off between civility and informativeness which just might not be there.
Establishing a culture of following those rules is important to getting mailing lists that can sustain such discussion productively.
Calling Crocker's Rules exposes people to the expectations and reminds them what are striving to achieve, assuming that they are indeed trying follow the rules but got caught in the moment, which happens to most of us.
Furthermore, what's the point? I mean, if you're in a discussion group where there's a non-zero probability that one of it's members will pick slavery (or something else equally apalling) as a discussion issue, but group members are self-selected (which is a reasonable supposition for groups in general, and even more so for obscure mailing lists) then it's likely that all members are amoral enough for discussion purposes such that this "Crocker's rules" thing would be redundant.