Yeah, they're hot-keys for various things in a lot of games. If you've spent much time playing PC FPS games of the old-school type where your dude can carry a whole arsenal at once, for example, then you've had to get very good at quickly and precisely striking the entire number row with your left hand, since they're typically used to swap to a specific weapon, plus sometimes some of the F keys for other reasons (thinking in Jedi Knight, where F-keys are used to trigger force powers or healing in the default layout). Or any of the old-school keyboard + mouse or keyboard + joystick simulator games where almost every button does something, especially if they're combat oriented simulators (since that adds a lot of urgency to needing to hit many buttons very fast) like Mechwarrior or X-Wing/TIE Fighter.