Designers Guide To DPI

A standard movie, shot at 24 or 30fps, looks better in a 120hz screen vs a 60hz one, even thought there are still only 24 different images to be displayed per second, and both refresh rates are much higher than the available frames. A higher refresh rate means the screen can switch between frames faster, so it's actually displaying repeat frames, but the reduced ghosting makes everything look sharper and smoother.

In addition to that - ignoring the snarky paragraph underneath the picture - the example given where you have more intermediate states only applies up to 60-66fps; after this point humans are unable to detect any difference, due to ~15ms of visual delay and afterimages (ghosting!). People often mention studies where someone was able to detect an image displayed for 1/200th of a second or similar durations, but that doesn't mean that person can tell apart a moving image at 60fps vs 200fps. Our eyes have no shutter; we can capture light that was visible for way less than 1/60 of a second, but as soon as it starts moving our hardware limitations show up.