Earlier quoted context omitted.
The moderation system is one of the things Rob and I are most proud of. We set out to make a system that would allow for anonymous postings while avoiding it turning into Usenet. I think, with some hiccups, we largely succeeded. We also took careful steps to make sure that we get anonymized all the data; all the IPs and subnets are hashed, so even we can't go back and find the real IP while still having something to…
You guys did great! Nothing in the world even comes close to /. moderation. Reddit is a prime example of a simple karma system going off the deep end. Instead of reinforcing good behavior, the trend is now that a substantial majority of the community competes for karma score. The noise level has increased sharply over the previous years such that the "popular reddits" are now in the same domain as Digg or 4chan. (Tha…
That's only recently been the case, and the majority of the HN community still seems to be against it. If anything I've noticed more low-quality comments that haven't been downvoted lately, but that could easily, as you suggest, be a result of changing demographics and not connected with hidden karma. Unfortunately, as any community grows larger there will be a lowering of overall quality, though the number of high-quality comments may remain the same. It's the perception of lower quality that drives away the best members, so a preponderance of low-quality comments obscuring a number of very good ones can have a disastrous feedback effect.
I recall reading that part of pg's decision to start HN was as an experiment in entropy-avoidance. To that end, he has never sought to grow HN's traffic beyond that which the community could absorb. Now that HN is constantly mentioned in blogs, techcrunch, on facebook and g+, that might not be a viable strategy anymore. I eagerly await the changes he has in store for HN.
As for reddit's karma system being broken: that's not the problem. It's the demographic. The karma system works great in subreddits with a good community, and terribly in some of the larger subreddits with more of a 4chan/facebook crowd. Determining visibility by voting is only a problem when the voters are idiots. Also, as much as the HN community (many of them current and former redditors) may decry the devolution of reddit's overall quality, we really aren't the target audience. Reddit is a business that makes money through growth, and the overall reduction in quality has coincided with a huge surge in popularity and profitability. That's no accident. We may not like it anymore, but that's not an indictment of their business model or strategy.