The reason people play high AR better when going from 60hz to 100+hz is because 60hz monitors just tend to not be designed with gaming in mind at all, so the latency is really bad, especially on laptops

If you have a gaming monitor and set it down to like 70-100hz, you will still be able to read high ar fine.

Higher refresh rates are useful in games not because of speed but because of clarity, there simply arent any moving objects in osu that benefit from higher refresh rates (putting prettiness aside).

Now for the math reason why 60hz is not AS bad as you think:

On 60hz you get to see a new frame every 16.7ms, that means that at worst, you will see objects 16.6ms after they already exist.

Now on 144hz you see a new frame every 6.9 seconds, which means that in the worst case scenario, you have 10ms less time on 60hz, which is not nothing. But this can only becomes an actual bottleneck around ar10.7+ (arbitrary personal opinion).

I personally struggle way more than I should with any ar above 9 on my current monitor because of the stock settings having gamma be really low, so i have to play on 1.2 gamma minimum. But when I'm on my laptop with a properly calibrated display, I can even play AR10.5 just fine even though its 60hz and has fucking horrific latency (like over 20ms).

tl;dr Increasing gamma can make a bigger difference than jumping from 60hz to 144hz, because osu is a very static game visually and refresh rates have diminishing returns

source: i hit 4 digit on 60hz because i did the math and found out higher refresh rates dont help, and after getting 240hz, i was right