Ask HN: Why are hn discussions of a higher quality?

Clearly a very subjective topic so work with me here...(and forgive my clumsy explanation).

Comparing hn to other discussion boards I'd say it has far higher quality discussions yet I can see no obvious signs of moderation. (Or even aggressive algos like reddit).

Responses are generally well reasoned, low on personal attack & other undesirable traits. Criticising people frequently results in introspection on their part rather than blind retribution.

All this is great of course...yet leaves me a little confused as to what the magic behind the curtains is. What's different vs other discussion boards?