I have to say, I'm guilty of short humourous comments on HN and I feel slightly bad about doing it.. because there's reddit for relaxed convos, and HN was more about deep chat about tech related articles / texts.

I think it's good to keep the quick fun under control.

I don't think it's a zero-sum game. Get where you're coming from, though. If the joke comments consistently got more upvotes than the serious ones, it would make threads unreadable.

That said, I think there is a happy medium which isn't entirely po-faced.

It's not that. It's a combination of the guidelines discouraging insubstantive comments -- to keep the signal-to-noise ratio high -- and genuinely good jokes being hard to do.

Most of the time, if I try to crack a joke, it gets downvoted because it's insubstantive and not all that funny. Once in a while, I've gotten a fair number of upvotes for a humorous remark, such as this one under my old handle:

https://news.ycombinator.com/item?id=14995810#14996229

IIRC, it hit high 50s for total points.

Of course you are, but it should be good.