I think the word “strength” is often looked down upon and taboo because people associate it with “brute” – like a savage beast using his enormous strength in a dumb, inefficient manner.
But strength and efficiency don’t have to be a dichotomy.
I agree that angles play a massive role regarding Qinna, but just because you don’t need to use a lot of strength doesn’t mean that adding strength won’t help.
Picking up a boulder with my hands might be seen as dumb strength. If I put a lever under it, I suddenly don’t need a lot of strength to lift it. But if I add a lot of strength in combination with that lever, the boulder is even more easily moved.
The lever is just a force multiplier. But in order to create that lever, I have to stop picking the boulder with my own bare hands. So we may be taught to "not use strength" because I am trying to develop something that doesn't rely on a lot of strength. Once that part is well developed, I can then add strength on top of that.
Once the subtle side is well-developed, adding speed and strength on top of that only helps.
There are Qinna methods that can be done with Fa Jin – done with a crisp power, like a jolt. Basically, if the slow/soft approach already hurts a lot in a laboratory setting, the fast and powerful approach will hurt a heck of a lot more.
Regarding Dr. Yang, he wrote in his White Crane book: “60 to 70% of the techniques which I have documented in my Qin Na books originated with Master Cheng.”
It seems that the majority of his Qinna methods came from his White Crane teacher.
Since Dr. Yang was born and raised in Taiwan, that’s an excellent place to learn White Crane because it’s so close to Fujian province which is where White Crane came from.
I personally think that White Crane is what Dr. Yang is best at. I think it was his first martial art and he spent like 13 years learning it which is far longer than any other martial art he learned.
However, to my surprise, he also wrote in his White Crane book: "I spent thirteen years learning White Crane from Master Cheng, Gin-Gsao, and did not even complete half of his training."