Comanglia#40
Why does it matter that the video is 4 years old? That doesn't change how crazy the shots are. Also, AFAIK, Hal never changed his monitor from the one seen on the video(at least up until mid 2015, when he was still winning CPMA and now Reflex cups). It's actually certain he still used a "75Hz Samsung" up to 2014, because he has commented stating so in that same video, on 2014.
I went ahead and did some digging around about Powah, and I'm afraid you're mixing things up - here's a 2015 tweet from him showing his gaming setup, with two cheap lcds: https://pbs.twimg.com/media/CMpRn-eWgAARrOj.jpg:large
AFAIK one of those is his old monitor he has since forever, and the other is a new one that's still 75Hz though...
I myself have a BenQ 120Hz and as much as I like, and believe I can feel the difference, I'm still able to play just fine after a brief period of adaptation on ~2200 elo QL lolCA... if that means something heh (just to make clear, i'm arguing 120 is better, but not a requisite - speeecially for non hitscan)
Edit: Also, on your argument about every scout in invite using 120/144Hz: IMO it could be more of the fact that they can/belive they need to do so than that they actually need to do so.