I get the notion of not allowing it to devolve, however I do think it should be OK and acceptable to upvote someone for truly making a humorous or clever comment. I work with a lot of clever people in my job, and humor (even bad humor) is part of our daily camaraderie and social interaction, so in some ways it's second nature for me to want to post humorous comments.
Not to over complicate the comment system here but I wish one could just tag a comment as "humor" and one could then choose to just not show them if one did not care to see such things.
The distinctive thing about the type of reddit humor I think they're talking about is how referential it is. You don't so much make a clever joke as invoke the standard joke on its trigger phrase or subject.
I see plenty of jokes on HN but they are usually part of a comment that would be made anyway. Joke-only comments also aren't that rare and when they're clever and specific to the context are usually pretty well received.
Not to over complicate the comment system here but I wish one could just tag a comment as "humor" and one could then choose to just not show them if one did not care to see such things.