Clearly we aren't at the pinnacle of linguistic evolution. Ancient Greek and Latin were far more evolved than modern Indo-European languages. Indo-European languages have been going downhill for the past 2000 years or so ;-)

All this is true. Nonetheless, if you go too far towards the other extreme and apply Humpty-Dumpty's theory of language ("When I say a word it means exactly what I want it to mean") you won't be able to communicate at all.

http://www.sacred-texts.com/neu/eng/eft/eft43.htm

I hear that argument a lot, but I rarely see a case where someone notes "wrong" usage — like you did — where there's actually any ambiguity. Like when people complain about "literally" being used as an intensifier. I doubt they're confused if the speaker e.g. actually died of embarrassment or if they're just using it as an intensifier.

Language has so much redundancy that a slightly different understanding of a single word in a sentence rarely is of any consequence.

Again, everything you say is is true (which, BTW, is why I prefaced my comment with "Just FYI..."). But the sarcasm/ironic-humor confusion is very prevalent even among native speakers, and in a different set of circumstances it could cause confusion or worse because the implied stance of sarcasm is the exact opposite of ironic humor. Also, HN is a public forum, and comments are read not only by their respondees but by lurkers as well, some of whom may not be native speakers and who might therefore appreciate having some of the subtleties of the language pointed out to them.

After reading all the comments here, you still stand behind your original pedantic comment as being appropriate and productive? Fascinating.

If you knew the OP was more likely to feel insulted than to feel helped, that wouldn't have changed your action?

Well, we don't have to speculate. The OP weighed in:

> Just to be clear, I quite liked Lister's [sic] note as well.

So yes.