Earlier quoted context omitted.
I absolutely notice if my monitor runs at 60hz for whatever reason instead of 144hz, even while just doing desktop tasks. Have you used a 144hz screen for any significant period of time?
Just go to a place where they sell iphones and compare the 60 Hz to the 120 Hz model. Open the settings menu and just scroll up and down. The difference is so very noticeable. I don't know why people try to claim that it's imperceptible, or that you can't tell the difference between a 1080p and 4K display.
So then I replaced a PC monitor from 60Hz LCD to 144Hz 4K LCD, I expected such difference before buy. After setup, I can find difference but don't find much difference like smartphone. I don't scroll so much on bigger screen PC, and maybe I'm too used to Windows' crappy scrolling. Anyway my mouse has classic wheel so non-smooth scroll is fine unlike touchscreen/trackpad case. Mouse cursor isn't smooth but it's just that. Finally I bought second 60Hz 4K LCD after that because it's cheaper, it's fine.