Some time ago I tried to create a discussion forum software which embodied this kind of classification. Users could write what they liked (including trolling and name-calling) but all responses had to be given a"type" which readers could use to sort and filter the threads. "Moderation" was only through type-changing (ie. the supervisor could reclassify a reply from "counter-argument" to "name-calling" meaning that it would probably get filtered, but not delete it entirely)
The software didn't really make it, but there's some interesting discussion here : http://www.nooranch.com/synaesmedia/wiki/wiki.cgi?TypedThrea...