I agree that input latency matters a LOT but disagree about 120hz being some sort of sweet spot.

On the input side, yeah even a few 10’s of ms is very noticeable when typing or doing something quick.

But also I use 240hz monitors for everything, and when I had a config bug on my Mac that degraded my connection to 180hz, my computer felt slow and laggy, and I only realized when it drove me crazy enough to check the settings again. I’m sure the same would happen if I was on a 480hz monitor and it got degraded to the 240hz that I’m used to now.

And I agree there are diminishing returns, but there are still very perceptible returns.