Im sorry but that is the biggest load of horse bunkum ive ever heard.
YES sims (along with any other game or video source) are perfectly viewable at less than 60fps. If your eyes and brain can process 60fps then you my son need to go to a university and be studied, coz you are a medical marvel, you have a gift NOBODY else in the world has ever had
Not even Walt disney, the massive racist, himself could see see at that speed, and he could see single frames in his cartoons.
What you are getting confused over is the difference between a CONSTANT frame rate and a variable/changing frame rate. The average human will NOT see faster than about 25 fps. so 60fps, you are just wasting 35frames.
Movies do not stutter, tv does not stutter. but yet they are done in 24,25,29.9 fps so why dont they stutter? because they run CONSTANTLY at that speed.. When you see a stutter in a game, thats not because its dropped below some magic number, its because its dropped, that simple. Generally speaking, you are not seeing slowness you are just seeing a speed change (either up or down it doesnt matter). Even if the game was running at 90fps, if it suddenly changed its speed even by 2 fps, then went back up to 90fps right after, you would still see a stutter. becuase its just dumped 2 frames out, so you see the game suddenly go from here.................to here, in an instant, which looks like a jump in the footage.
But no the old myth of games MUST be run at 60fps or better is just that, its a myth. If you can make the game run faster than say 30fps (and this is the important bit) and stay at that speed then you will NOT see a speed problem. its only when you are at say 40fps and you drop to 37 fps for a split second before coming back up to 40fps that you notice things. It will do it the other way as well. If you are running at 60fps ad it goes up to 64 then drops back to 60 for a fraction of a second, again you will see a stutter.
So no... 60FPS is not some magic number you should all be trying to reach, it is a number some person came up with to make everybody else try and reach, years ago..But it means absolutely nothing.
The only time this is not true is when the FPS is below about 25 because thats the speed you see things, so slower than that you see the tiny gaps between frames. Anything above that, as long as its constant, is perfectly fine..