Why does GIA provide fewer grade categories for color and clarity for laboratory-grown diamonds?

GIA has always used different terminology to report the color and clarity grades for laboratory-grown diamonds. GIA’s Laboratory-Grown Diamond Report, which replaced the GIA Synthetic Diamond Report in July 2019, use Colorless, Near Colorless, Faint, Very Light and Light to report the color grades for laboratory-grown diamonds rather than the D-to-Z scale used to report the color grades for natural diamonds, and use Flawless, Internally Flawless, Very Very Slightly Included, Very Slightly Included, Slightly Included and Included to report the clarity grades for laboratory-grown diamonds.