[ThinkingPlus]

Not sure but you can still get some Non-OEM drivers without grooves. I remember Yonex made some OEM drivers several years ago that had no grooves. The lack of grooves was supposed to cut down spin drastically and therefore be more accurate and longer.

Marketing and hype. The grooves on a driver are primarily cosmetic and tradition. Angle of attack at impact, mass distribution of the head, and shaft tip dynamics influence spin off the driver (other things as well I am sure). In fact most of the long drive guys use drivers with no grooves. It allows them to get thinner faces without caving the faces in.