A common misperception. Humour on HN isn't verboten as such, it just needs to be carefully cloaked in some sort of substantive contribution to the discussion. It's empty responses, not funny ones, that draw the downvotes. The kind of humour that predominates on other websites, unfortunately, happens to be of the empty variety and so recent immigrants from there tend to draw flak for one-liners that don't convey any information.
SNR is prized and cultivated around here. That doesn't rule out humour per se, but it does considerably shrink the set of humourous responses that are appreciated.
blah blah blah. I happen to DISAGREE that "The insinuation that it's all just done for the grant money". The insinuation is jokes. Hence the lack of a sense of humour. The original objector didn't just not like the TLDR comment... he didn't get it and read into it way too much negativity. And I happen to think he was wrong about that.
You're missing the point. You can disagree all you want, but do so in a way that contributes to the discussion. Sarcasm rarely does so, and is generally frowned upon. So too, for that matter, are ALLCAPS and such rejoinders as "blah blah blah"
It has nothing to do with humor, it's about noise. You can be funny while also contributing to the conversation, but posting jokes instead of contributing will tend to get down voted.