OK. What happens is, generally on PC games, physics (and thus game speed, timing, etc.) are run on a different timer than frames.
Thus, your physics/game engine can be locked at a stable rate, say 60Hz, which all configurations will strive to maintain... while the more fickle frame rate, which can vary very wildly based on hardware configuration, won't affect your game.
On consoles, a simple shortcut is used where, because older consoles automatically locked the video frame rate onto the TV's refresh rate. Since you have a specific target architecture, which will NEVER vary, you KNOW what your frame rate will be at any given time, and can usually lock your performance to a certain 'average' frame rate.
The games then would very often simply use the reliable frame timer to take physics/engine samples. This can easily be seen in some games, for example in Mario Kart 64, in Battle mode, on the Rooftop, the game very noticeably speeds up tremendously at times... easy way to see it: Have one character with triple shells out, and have EVERYONE go to teh very edge of the stage. The shells should spin VERY QUICKLY. =)
Basically it's just to keep your performance better in a console environment... but that's why the games can't go past 60fps easily - the games' physics engines are looking at your frame counter for update cues.
