Hemi that graph there is correct on paper, but so are graphs showing that the human eye can see a max of 72 fps or so. When everyone who plays games knows they can tell a difference between 60 fps and 100 fps easily if they are tested on it.
On youtube, when you find a 4K video, you can easily tell the difference between 1080p and 4k. It's both the crispness and the feeling. Even if a monitor cant see 4k in a picture, it can see it in a video, because everything is fluid and the "averages" can be seen at a higher rate.
I saw Fallout 4 on 4k at the PC Room here and it was fantastic, and it was only a 1080p monitor. But there was a definite difference