Ugh...
http://www.100fps.com/how_many_frames_can_humans_see.htm
At the end of the article: pretty much depends on your eyesight but at a point it becomes \\"all in your head\\".
And that does nothing to suggest that the point at which it becomes "all in your head" is 30-40fps. There is a limit to what humans can see, but it's not down around 30-40fps for all people, and probably not even most people. (Back in the days of CRTs, I'd notice flicker below 85Hz. Even just walking past a bank of monitors at a computer store I could tell which ones were at the default 60Hz and which ones had been set higher).
Go ahead, try out the side by side comparison for yourself. See if you can spot the difference. I was sure I wouldn't, since I'd been gaming on old hardware when I first tried it, and didn't reach 60fps as a maximum in some games. I was quite surprised to see that it was noticably smoother.
EDIT: After doing more than skimming that article, I have to wonder if you even read it yourself. "To have a perfect illusion of everything that can flash, blink and move you shouldn't go below 500 fps."
Five hundred frames per second. Certainly that's not the requirement for every gamer in every type of game, but it certainly debunks the idea that your link proves the human eye is limited to 30 - 40 fps.