Yes; it's true of all the tubes in a frame and fork. The higher strength alloys - because of their higher ultimate tensile strength and yield strength - can be drawn with thinner walls than lower strength alloys like plain carbon steel, and thus can be lighter because there's less material. The thinner walls, though, will make the tube flexier. Going to larger diameter tubing like oversize (OS) or double oversize (XL) restores stiffness lost due to thinner wall thickness while still saving weight.