Sarcasm itself is not banned here. The community pushes back against sarcasm because it is often associated with poor quality comments. I've quoted some comments by dang about sarcasm with links to his source comment - it helps to read his well-thought-out opinions within their context.
The guidelines don't rule out sarcasm. They ask for comments to be civil and substantive. The Venn diagram of those things may not have a lot of common area but there's definitely some. Just don't ask me to specify what it is—that's probably too hard.[1]
The community here avoids sarcasm not for the reasons you so condescendingly note, but because sarcasm tends to reduce discussion quality.
Readers here recognize sarcasm, but they also recognize what happens to a web forum where it is allowed to proliferate.
We don't have any problem with satire and sarcasm as such, but on a large public forum like HN, with everything a mile wide and an inch deep, they are nearly always associated with really low-quality discussion.[2]
The logic is similar to why jokes are discouraged[3].
I've often wondered why jabs, swipes and sarcasm are so corrosive on HN when anyone who knows about the history of discourse knows what a lively role they have played. [The lack of sarcasm] makes the discourse a little more bland, but the alternative is not lively exchanges of high wit, it's YouTube comments.[4]
I think sarcasm is more of a problem on HN than lame humor is. Humor doesn't always succeed, but at least it's intended to make others feel good. (Think "good humor".) Sarcasm is only marginally related to humor. It's really about scorn. Sarcasm is verbal bile. It feels good to let it out, but it acidifies the environment. It feels like you're being smart[5]
Like you, I love sarcasm (New Zealander's tend to slather it on) and when used well it is a often a subtle compliment to the receiver. Over the years I have learned to tone my sarcasm down because I tended not to use it helpfully and respectfully.
Note that Dang seems to personally like to use sarcasm[6].
[1] https://news.ycombinator.com/item?id=10411394
[2] https://news.ycombinator.com/item?id=18506429
[3] https://news.ycombinator.com/item?id=18284457
[4] https://news.ycombinator.com/item?id=9378899
Note that my comment is directed specifically at /s and not at sarcasm in general. I understand very well that given the diversity of opinions on internet it can be challenging to tell it appart. So I agree that in many case one should abstain. But if you go ahead and still use it, please, by all mean, don't botch it. Better to double down and make it obvious or ridiculous than this silliness.
You seem to be really upset about this, and I feel for you how much you will suffer over the years when people don’t do things the way you think they should.
/s