Unfortunately this statement is incorrect. The type of panel does not determine the gamut, it is the backlight. iMacs use standard white-LED backlighting, which only covers the sRGB colorspace ("standard gamut"). Wide gamut monitors are better for photo editing, since they can cover ~98% of the AdobeRGB color space. The reason you care is because printer ink (particularly inkjets) can print colors beyond the sRGB colorspace and even a little beyond AdobeRGB in some cases. So by using a wide gamut monitor you can more accurately utilize the full color gamut of the printers. If you do your printing on a lightjet (or Chromira, etc) that uses the more traditional silver chemistry, the gamut of those outputs is usually just about sRGB so it is not as big a deal.