I might be the only one who feels this way, but I doubt it. New users aren't all bad, and I can't imagine that the purposed decline is all our fault, either. However, the sentiment might be helping fuel the rate at which "bad" users join. Someone who has surfed for awhile and is thinking about creating an account is going to feel turned off for many of the same reasons why you don't jump on a sinking ship[0], but the trolls, etc. won't care either way. Just a thought.
[0] - I'm not implying that HN is in anyway a sinking ship, I derive a great value from it.