I thought so too, but for a while I had 2 144Hz monitors on my Mac Pro[1] and very much noticed it in the UI, window dragging was smoother, browser scrolling too, absolutely noticeable.
[1] Then Apple released the Pro Display and Big Sur and people wondered "how does the math work for a 6K display and bandwidth?" The answer, they completely fucking broke DP 1.4. Hundreds of complaints, different monitors, different GPUs, all broke by Big Sur to this day just so Apple could make their 6K display work.
My screens could do 4K HDR10 @ 144 Hz. After Big Sur? SDR @ 95 Hz, HDR @ 60Hz. Ironically I got better results telling my monitors to only advertise DP 1.2 support, then it was SDR@120, HDR@95Hz.
Studiously ignored by Apple because they broke the standard to eke out more bandwidth.
