You had to... RAM was expensive. In 1980 I programed a Vic-20 in machine language to emulate a roulette wheel, complete with the sound of a decelerating bouncing ball, a whir of the rotating wheel and a display on the screen of the wheel, resolving to an image of the ball in the pocket of a slot on the wheel... with a quasi-random number generator to determine the slot. When I was finished, I had ONE byte of the 3583 Bytes of suser RAM space left. Any changes that used that one byte resulted in a crash. It was the wonder of my Lodge's annual casino night!
I think I saw an episode about you on Breaking Vegas.