The much bigger difference is that Wikipedia conversations/disputes are long-running and relate to the state of permanent artifacts.

The technology of Hacker News makes it literally impossible to carry on a long-running conversation or collaborate on serious permanent artifacts. There’s no point in going back to last week’s discussion and vandalizing it with troll comments, because nobody is ever going to read it. There’s no need to invent complicated rules for productive collaboration, because there’s no work to collaborate on in the first place.