Many displays, be it CRT, LCD, Plasma or OLED, have a default response characteristic close to a gamma of approx. 2.2-2.4 (for CRTs, this is the actual native behaviour; and other technologies typically try to mimic CRTs). A target response curve for calibration that is reasonably close to the native response of a display should help to minimize calibration artifacts like banding, because the adjustments needed to the video card's gamma tables via calibration curves will not be as strong as if a target response farther away from the display's native response had been chosen.