Both schools of thought have valid points. The difference lies in the specific exercises and what you do to warm up. Building muscle mass can strengthen you but it can slow you down if you don’t engage in some flexibility training. The only thing that strengthens your technique is practicing every day and trying new things. In short, working out is a double edged sword. Use it properly or it WILL hurt you and your technique. Work hard and weight lifting will help. Another helpful tip, if you just want to increase stamina or tone your muscles, use a small amount of weight but do a lot of repetitions. Visa Versa for building mass. simplified:
More strength: more weight, less reps
More stamina: less weight, more reps
But always, always, always, always, always, always, always, always, always, stretch and warm up!
You can build more muscle mass than the hulk and tone it all beyond Ahhnuld’s physique but you won’t be able to bend over and touch your knees if you don’t stretch out before hand.
learn your limitations and don’t over-do it. Remember the double-edged sword thing.