I am assuming you are already convinced on the importance of exercise. And if you scroll down a bit, I will break down the differences between mobility, flexibility, yoga, and stretching in careful detail. Without sufficient mobility you cannot be all that you wish to be. This applies whether your chosen craft is golf, strength training, CrossFit, or endurance running. You are not as efficient as a runner, you are more likely to get injured as a golfer, you are slower in CrossFit than you ought to be, and as a power lifter your recovery times are slower.
Mobility is critical for all sports and physical activities. Period.
This book provides an overview of the research and history that Gray Cook and Brett Jones sells at FunctionalMovement.com. While dated, the techniques explained for the Functional Movement Screen (FMS) and Selective Functional Movement Assessment SFMA are really the same today as they were then.