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.
Functional Movement Book Review. This covers more than just the FMS and SFMA although these topics are explained in detail. The Movement Book helps lay the groundwork on how to improve human locomotion.