Everyone thinks since Colin Morikawa, and John Rahm have a weak grip, they should as well. Unfortunately, this thinking has plagued many average golfers through the years. Don't use these guys as your determining factor on what grip style you chose. They're freak athletes and can time the body dynamics needed to make those grip styles work.  When doing our grip studies we determined that the strong grip was the easiest grip to create speed, and control the club for the average golfer. It's also the easiest way to swing on a sideways angle so you can control impact and into the follow through releasing the club "down the line"