This is controversial because people overestimate how funny their jokes are, especially to a large general audience, and prefer to interpret downvotes as humorlessness of others. I think scott_s described this best: https://news.ycombinator.com/item?id=7609289. (Note the phrase, "When you have N people"—it explains many things about HN.)
HN's culture is probably also influenced by Reddit loss aversion syndrome, given that it started as a kind of alt-Reddit (I don't want to say anti-Reddit!) and still has the younger sibling's tendency to compare. As a Canadian I'm tempted to say we're Canada to Reddit's U.S., but I may not be allowed to say things like that any more.
There are some "humorous" sarcastic responses to this Ask HN, even if they were funny I feel they form a dead end to the discussion.
Sarcasm is verbal bile. It feels good to let it out, but it acidifies the environment. It feels like you're being smart, but usually is more of a tic, like eye-rolling. A community with high sarcasm levels is like a room full of eye-rollers—not a great place for conversation. I think that's why you correctly identify it as a dead end.
I'm a big believer in that you should do what you do best. Hackers are often smart, informative, insightful and knowledgable about lots of stuff, but rarely are they funny. There are way better sites to visit if you want funny.
I guess users avoid it for the same reason you don't tell naughty jokes in the workplace: It's just not the right place.
On the other hand, I read many comments who were funny AND insightful, especially in XKCD and Dilbert threads.
Throwaway lines are rarely well received because they add minimal value (if any) to the conversation, which is HN's primary criteria. Where humor is well done, and adds value, I've always found it to be well received.
See, for example, one of my 'highest rated' comments in a discussion about 'The Miracle of Compound Interest'. The OP (now offline, so iirc) argued in favor of higher estate taxes because compound interest over future centuries guarantees wealth would become unfairly distributed to a small number of families. I chose humor to pick holes in the theory rather than economics - https://news.ycombinator.com/item?id=812221
[Edit] I realised some throwaway lines do add value, when I remembered this comment in a discussion about eating bark after the collapse of civilization received even more love than the OP - https://news.ycombinator.com/item?id=842857
Posts and comments which are more lighthearted but still provide additional insight are fine, though. https://news.ycombinator.com/item?id=8140290
Yes, I am being a little hypocritical with that example. :p
On a related note, I'm surprised that ChangeTip hasn't been implemented here (though if it were, I imagine it would quickly get banned)
HN's always been sort of a refuge from those sites for that reason. It's a place to discuss software seriously.