There can't be general purpose reputation online. It's meaningless. There can only be reputation for specific behavior. Someone who has a lot of positive reputation on Ebay is reasonably likely to fulfill your order, assuming your is similar to the previously filled orders - check if all his/her other orders were for $1 and your's is for a million.
Just about any other karma system winds up measuring how hyper-active someone is online. My karma score tells you nothing about me at all except that I'm here a lot and talkative.
This can be good thing. Much real life bad or good reputation is unjustified.
I don't know that it's going to happen anytime soon, but I can see exchanges between karma and real currency eventually leading to a reputational economy. See Doctorow's Down and Out in the Magic Kingdom. http://craphound.com/down/download.php I wish that pg would start allowing karma transfers here so we could start experimenting and I could cash in all of my stupid points, but that experiment is not one of his goals.
For a while I've told myself that I'd like to auction this username for charity, mostly just to see what happens, though I like the idea of converting my years of activity here into a charitable donation.
On Hacker News, karma really does just measure activity. My point is that it is theoretically possible to give karma more meaning than it has today.
A likely implementation seems a box where you type the username and points for the transfer recipient. I believe this was discussed a while ago, and someone mentioned that they would do programming work for karma.
I have the karma and it doesn't mean anything to me, but it means something to some people that don't have it. There are people out there that would trade real world goods and services for Hacker News karma.
The point would just be as an experiment. I'm not expecting anything good would happen immediately; we'd probably see more abuse than anything.
I mostly agree with you, but it's not hard to create a karma system that isn't just a reward for hyperactivity. For example, Hacker News could change its system so that nobody got a point simply for posting a comment.
But however fine-tuned the system, no point system is immune from gaming, and no-one can expect points to be any more than vague clue as to someone's true worth as a participant in the community.
Karma/Reputation systems on website are to reward a desired behavior. Part of HN's value is it's active useful conversation (vs /.,digg etc). So it makes sense to give the community the tools to reward what they want and create positive self feedback. (Also like the other reply, simply posting doesn't give you karma)
There are two problems with what you say. First, a large number of posts with a small number of upvotes is still valued more by HN than a small number of well-respected comments. Second, moderation systems tend to be inflationary, which means that the point value of a given comment has more to do with how many people read the thread than anything else.
Slashdot's point cap is the obvious solution, but even there comments tend to lean heavily towards +5 on well read threads.
Re: first problem: I think a large number of fairly good comments probably IS a more valuable contribution than a small number of very good comments.
The second problem is more, er, problematic, but you could argue that good comments are popular articles deserve more karma, since these are comments on topics which people are really interested in – i.e. valuable insights on hot topics benefit more people than valuable insights on obscure topics, and are therefore more valuable contributions.
I agree that voting systems on the web end up favoring the most persistent, rather than the most worthy or highest quality. This is something that I've seen on Wikipedia and Digg. And to an extent with the trolls on Kuro5hin.
I think moderation is important, but that it should not be the central aspect of user interaction.
Just about any other karma system winds up measuring how hyper-active someone is online. My karma score tells you nothing about me at all except that I'm here a lot and talkative.
This can be good thing. Much real life bad or good reputation is unjustified.