We've all seen salt in a shaker. Its hard and crystalline. After enough use, the glove absorbs enough salts that it becomes hardened. The harder it gets the less traction it provides. Eventually, your glove is actually slicker than your bare hand.
Traction is important.
Don't drive on slick tires. Don't drive with a slick glove. Good Golf P.S. Golf gloves are half of the traction picture. Grips are the other half. Fresh grips feel tacky.