In the aggregate, karma is a measure of volume, not of quality. Members with lots of karma are often the ones who spend all of their free time writing comments

In the aggregate, karma is a measure of volume, not of quality. Members with lots of karma are often the ones who spend all of their free time writing comments and submitting links, focusing on quick, easy wins. There's no reason to think they're the ones with the most discerning taste. Using average karma per comment would be an improvement, but it still favors people who are on the site constantly (so they can be the first to make the obvious comment that everybody upvotes) and frequent the most popular (and lowest effort) subreddits. Another problem: the last thing reddit needs is more incentive for users to improve their personal karma score. Karma is useful for readers, but that benefit is balanced against the incentives it provides for writers to optimize their karma score above all other considerations. I think HN achieves this balance better than reddit does by deemphasizing personal karma scores in various ways, and this is reflected in the user experience. It's bad enough when karma's just a driver of personal gamification. If it actually provided users with social clout and ability to frame the conversation, well, then it would be something with real world value. You wouldn't need click farms to manufacture viral content, just a few well-placed accounts with high scores. High-karma upvotes as a service. As a side-gig for a careful power user, it would be nigh-undetectable. Think of the difference between HN and reddit, then multiply it 10-fold. I think that's what you would end up with.