I came to HN well before I found Reddit (I think it being mentioned here was the stimulus). [this is my 2nd username here]

HN thrives IMO because it got a high value kernel of contributors early on, through synergy with Ycombinators business, and because of strong moderation heavily focused against new users.

Up until the last year or so most comment threads haven't needed to be filtered, due to the relatively small population, but popular stories now attract a mass of comments such that one can't easily scan through to precis the range of reactions.

HN maybe wants to stay "small" though. A lot of users in any case want to keep a tight focus on start-ups/computer tech/programming; keeping a "clunky" comment system probably provides useful friction to that end.

The main frustration in consuming comments here for me is the lack of differentiation between valuable and disagreeable comments. Though this appears to reflect pg's personal philosophy (he stated that down-voting for disagreement was proper, or words to that effect).