In an age of 'alternative facts,' a massacre of schoolchildren is called a hoax
latimes.com
latimes.com
I think HN is deeply suspicious of CIA, NSA, Putin, and a few other state actors. While some of the theories about those organizations may seem like crazy conspiracies, we have so many examples of completely bat-shit insane real crimes by them that almost anything seems possible. Putin and the CIA, in particular, have done some truly egregious, horrific things. They seem capable of anything.
I'd be interested to know what other theories you're seeing, because outside of those, HN seems very reasonable and conspiracy-free.
I am observing more and more stuff from 4chan and Donald subreddit on HN.
I occasionally see MRA/eugenic bullshit here (i.e. "sexism isn't real" and "science supports the inferiority of certain races"), but that's relatively rare. This community seems to be overwhelmingly progressive.
Also, re: that specific comment: I agree with it. It may have been totally beside the point (I didn't read it in context), but it acknowledges that Pizzagate was probably nonsense while saying that it's possible that elites in the US commit heinous crimes with impunity. That has been true before and it could be true now.
Of course Pizzagate is total insanity and/or trolling, and I don't think Hillary Clinton's circle is a likely suspect in terms of sex abuse. But the Catholic Church scandal is a decent analogy: a very respected "moral" institution that completely ignored enormous amounts of child rape. Penn State's treatment of Jerry Sandusky's behavior is another. Not sure why the US government couldn't do the same.