Muscles hinder your WC energy. I see this becoming another ongoing argument between the different types of WC. Some use muscles, and some dont. Being that WC main concept is smaller beats larger, I think the style that doesn't use muscles and is based off structural stability and overcoming the opponents structure is the correct way. Other people will believe differently. Muscles get in the way and require complete relaxation to have them and not use them. Muscles tense up in battle and the more you have, the less WC energy will be delivered in the punch.
It comes down to the sifu and the instruction. I believe muscles are bad for WC, but good for health and confidence. My confidence comes from my WC and not my body.
2 cents
Sorry to ruin your theory but if you move your body it involves muscle, if you throw a punch it involves muscles.
Weight training is about resistance... If you punch air that is a form of resistance, if you lift weights, that also is a form of resistance.
What I think is the confusion here is that the concept of CORRECT weight training is misunderstood. You can lift weights without building muscle mass - plyometrics and whatnot. This is done to train explosive power i.e. speed training with strength resulting in a faster, stronger punch.
Correct technique results in an efficiency of movement that is faster and/or stronger. Adding other forms of training such as speed and strength makes the whole process more efficient still.
I kinda feel that I'm having a discussion in the 70s here....