For the pentagon, I have seen no evidence to the contrary, but the rest of your statement is wrong. Sorry I don't have time to go on a chase for citations for you, but there is plenty of evidence of Masonic influence (not that this is a bad thing) on the general layout of the DC area.
Which, to be fair, is a large part of why it is what it is. There are plenty of spaces where sarcasm, cynicism, and humor are not discouraged. There's something... peaceful about HN's norms.
Sarcasm doesn't translate to text very well at all. The comments that come after when people are mistaken about the lack of/use of sarcasm are pretty pointless and detract from actual discussion.
It does where readers understand the conventions. Repetition of words or absolutes points to sarcasm. "I never smoked pot" or "I have absolutely never ever under any circumstances even been in the same room as pot."
Repetition of words with similar meaning is also a common literary and oral communication technique for emphasis of important points you want the audience to take away.
So, yeah, it can indicate sarcasm, but it can also indicate the exact opposite. It oral communication, tone would usually disambiguate between the two intents.
The entire top comment thread belies this statement. HN humor just has a particularly nerdy bent, in a way entirely unlike the bleeding sarcasm you'd find on, say, Reddit.
