>It could be something as benign as upvoting only thoughtful comments here on HN instead of funny ones like on reddit/fark/digg that could bring about a long-lasting effect on the future of open discussion on the Internet.

I don't know; the highest voted comment I've had on Hacker News was one that was funny. By an order of magnitude.

What's wrong with humor, anyway? On reddit, it's easy enough to close an entire thread you don't find interesting to see what else was voted up.