Some people have monitors running a 60hz which limits them to 30 fps so they can't see a damn difference
super basic quick explanation: 60Hz is generally standard atm for monitors and that means it refreshes sixty times per second (thus the use of the unit hertz, 1/s), meaning that if you have a 60Hz refresh rate, up to sixty frames could be rendered every second to show any diff
at least that's what my understanding of it is, there are probably more technical details and quirks that i'm not quite aware of
i can tolerate 30fps but i can definitely tell the difference. it bothers me to play games for extended periods of time with 30fps or lower. ultimately it's the same game but it doesn't look nearly as good and it's hard to not see it
i remember playing sonic adventure 2 when i was little and seeing the framerate suddenly go up, and the only way i could describe it to my sister was that it "looks real"
