"These guys" took care to clarify what they meant by "irony" and "sarcasm", these terms not being equivalent. If you backtrack and explore the branches of this discussion, you'll see that their definitions are not equivalent to those I've used. They're practically opposite.

As for sarcasm, [snip]I'll take it here to mean "A sharp, bitter, or cutting expression or remark; a bitter gibe or taunt"

This is, indeed, in my experience, universal. Though I call it "snark".

For the purposes of this discussion, irony means "A figure of speech in which the intended meaning is the opposite of that expressed by the words used", [snip] Although cultures stereotypically differ in their affinity for irony, I've never heard or read that any group completely lacked the capacity to produce and understand it.

I'm not saying they're incapable of using what I call sarcasm ("A figure of speech in which the intended meaning is the opposite of that expressed by the words used"), I just saying that, as a norm, they don't, in the same way that a speaker of Japanese is not incapable of not addressing other people with the proper grammatical forms and honorifics; it's just that, rather than disrespectful, it comes off as stilted and agramatical. It's just not done, and it just sort of doesn't work.

Grice’s analysis of irony as an overt violation of the maxim of truthfulness is a variant of the classical rhetorical view of irony as literally saying one thing and figuratively meaning the opposite. There are well-known arguments against this view. It is descriptively inadequate because ironical understatements, ironical quotations and ironical allusions cannot be analysed as communicating the opposite of what is literally said. It is theoretically inadequate because saying the opposite of what one means is patently irrational; and on this approach it is hard to explain why verbal irony is universal and appears to arise spontaneously, without being taught or learned

I'm really seeing a problem based on a lack of consensus in common usage, here. ("such a broad definition will make it very hard to judge whether a culture lacks verbal irony")

Either way, the post itself does not explicitly say that "A figure of speech in which the intended meaning is the opposite of that expressed by the words used" is a universal feature of all languages. Some comments seem to confirm my postulations;

My limited experience in Japan was similar to Kel's in Russia. Sarcasm ("That was just great" and the like) *baffled people. *

No one seems to have replied to that comment.

How confident you are that if you had heard it in Japanese or Arabic you would have noticed and remember that?

Extremely confident, though of course studies prove that, for most people, confidence in one's memories does not correlate well with precision. Which I found puzzling, because in my case it did; I've only been confident on a false memory once in my entire life.