Some areas of reddit do similar things with similar results. AskHistorians and AskScience are the first two to come to mind. This may be a lot easier in places

Some areas of reddit do similar things with similar results. AskHistorians and AskScience are the first two to come to mind. This may be a lot easier in places where there's an explicit point to discussion beyond the discussion itself - StackOverflow is another non-Reddit example. It's easier to tell people their behavior is unconstructive when it's clearly not contributing to the goal. HN's thing may just be to declare a particular type of conversation to be the goal.