It's probably a reflection of the size of HN. The more popular it gets the more people are flowing in at the bottom, to keep the place from descending into mayhem the karma thresholds can be ratcheted up.
I can still downvote as well, so that may give a slightly better idea of the new threshold value (you're in the top 25 on the leaderboard, so it's hard to predict the threshold value from your karma level).
In any case, why isn't the threshold value set dynamically? Maybe something like "if the user is within the top 70% of karma earners for the past week AND within the top 85% of karma earners all time" then allow them to downvote. This way it always adjusts to the traffic on the site and doesn't need to be manually changed unless you want to tweak the parameters a bit.
Being on HN (no matter how much time you spend here) is probably one of the best learning experiences and ways to invest your time there is.
My daily reading list is usually just about exhausted by the time I go to bed, if HN gets any bigger I'll have to get more selective about what I read.
True - I started programming around 1½ years ago, since it seemed like a good skill to have. Without HN I wouldn't have come as far as I have, and would be oblivious to a lot of core concepts such as the MVC model and recursion. So thank you HN for teaching me stuff I didn't know before.
Downvoting is pointless. It encourages mass retribution against unpopular but valid topics.
As someone else said, if a topic is broken -- spam, stupid or otherwise useless -- it should be flagged appropriately. My two cents, or probably about six cents worth 1 cent in 1987 values.
Someone voted you down. I voted you back up again. At least voting up is useful! (Feels good, too.)
Seriously, while down votes are needed sometimes, I think they are overused. I often see a legitimate comment voted down because someone apparently disagrees with its contents. This is not what down votes are for.
It's his site. If he says downvoting is appropriate for expressing disagreement, then there's no basis for saying that isn't "what down votes are for".
He has built the site, and people are building the news forum. It appears (or perhaps "it emerges") that what they are using the voting system for is close to his vision but not 100%. Of course he can still guide it, but the crowd works its ways.
Particularly when you go "against the grain" on here. If I dare say anything negative about LISP, Emacs, the environment or business mentality, I get shot down straight away.
http://arclanguage.org/item?id=10254