That's true, but when it drops below 90/90 you're a lot more likely to experience motion sickness from something as simple as looking around. With the higher frame rates, the motion is perceived more naturally by the brain, and you're a lot less likely to become nauseous. For the games more intense movement, where your perceived movement is disconnected from your actual movement, you can get used to it eventually, as long as your system is pushing enough information to your eyes. I have a top of the line gaming computer and I could only play very short sessions of Elite Dangerous when I started, since the perception is that you're in a spaceship that's flipping and spinning all around. After several short sessions, my brain started adapting until I could play for hours on end.