MUSCLE GROWTH FOR GOLFERS
First things first...
You will not lose mobility when you gain muscle.
You will not mess up your swing when you gain muscle.
You will not lose feel, "look like a bodybuilder," or any of the other negative connotations regarding gaining muscle mass.
As a golfer, you SHOULD SEEK MUSCULAR GAINS...
Even more broadly, as a human, you should seek muscular gains.
I'll briefly explain 4 reasons WHY and then, the more important, HOW.
WHY #1: More muscle means more speed.
The larger your muscles are, the more force you can produce with them (generally).
More force production will allow your body to create more energy, and apply more positive work into the club.
More work into the club means a greater transfer of energy into the ball at impact.
More energy transfer, more speed.
Therefore, if we work back our logic - more muscle means more potential speed.
DISCLAIMER: Even if you pack on muscle, you need to apply that newfound muscle into your golf swing. You need to swing faster. You need to alter your technique to allow for more speed. Gaining speed is a COMPLEX PUZZLE - and gaining muscle is just one of the critical pieces.