Does it, though? The reason why I ask such a loaded question is because I believe this is actually part of the 'healthy community' framework. It can be thought of as the communities immune system responding to what they perceive as outside threats to the system and is, in my opinion one of the most well known phenomenon in internet communities that far predates HN.

The modern analogy of this problem is described as the 'Nazi Bar' problem and is related to the whole Eternal September phenomenon. I think HN does a good enough job of kicking out the really low quality posters, but the culture of a forum will always gradually shift based on the fringes of what is allowed or not.