Redditism 1: "It's the internet. You are allowed to swear." 
I hate when some very grown-ass adult says that because someone didn't cuss enough for their taste. I swear all the time in my posts here but I still find that shit really, really tryhard and it seems more immature than not saying the naughty word to me.
Redditism 2: Ending a rebuke with a question mark when it's not a question to make it sound extra snippy.
I've heard this being compared to a "vocal fry" and maybe it is, and coming from CA, vocal fries were often said out loud as a form of subtle hostility toward people perceived as lessers, such as retail and restaurant workers. If you need an example of what I'm talking about, it usually goes something like this:
Poster: "I think (opinion)." 
Redditism enjoyer: "You're wrong?" 
Redditism 3: "Do you need help? Who hurt you? Help is available if you need it, buddy!" 
This one is the worst one I can think of right now because it contaminates even the very possibility of showing sincere care and concern for someone else. It comes loaded with the implication that the person that was "hurt" or "needs help" is fundamentally wrong and should shut up. Fuck that ableist shit, forever. 
A Serbian film was the most disturbing film for me. Not in a way that had me thinking for days like come and see and the other films you listed but in a "did this motherfucker really put that shit in there?"
I've never seen it and don't want to. I know about the ending and whatnot, though. I think even putting it to film was more messed up than RFAD. A group of people wrote it up, showed it to other people, and they all decided "Yup! This is what we're gonna spend thousands of dollars to film!"
Honestly the worst part about Requiem was the stuff with the older lady on dieting pills. You have to worry about elderly people isolated from the outside world plummeting into psychosis.
Thats a good point. The director making it from her POV while confused and scared was well done.
How else are we gonna warehouse them?