To break a joint only takes 2-6 lbs of concentrated pressure. (depending on the joint, i.e. elbow, knee, wrist) Muscle built around the joint can help and hinder a person usually taking away some flexability if one bulks up too much, but that muscle mass can protect the joint making it harder to break or "submit".
So, yes, it doen't take alot of strength to submit or break an arm on a larger opponent.
And that Sifu's are mixing their WC/WT with these other popular and inefficient arts to keep student's happy.
(and yes, it is INEFFICIENT to use your entire body on a joint lock that only requires 5-8 lbs of pressure to aquire a break
Soooo......I've got questions.
Like, which is it, 2-6 or 5-8 "pounds of pressure?"
Like, which is it "pounds of pressure," or "pounds of force?"
Which joint are you referring to? Does it take the same amount (of force, pressure or whatever) to break a finger as it does an elbow? What about a shoulder?
What about a knee?
Which anatomy text did you derive that little factoid from?
Do you mean "break the joint," or "rupture the articular cartilage capsule?"
Perhaps you mean rupture the medial ligament and collateral ligaments, also called the "joint capsule", releasing synovial fluid though I doubt it-maybe "rupture the annular ligament?" Maybe just "rupture the lateral epicondyle," though, again, I doubt it.
Have you ever actually "broken a joint," or had one broken?
Do you mean "use the whole body" for the movement devoted to the kansetsu waza, or use the whole body to control the other person's body?
Or neither, perhaps?
The irony is that people who train an art don't bother to look to their art to discover what can be used against another arts technique that may have defeated them. They just run like sheep to the other art.
But, if I understand you correctly, you have no problem with a "chunner" cross training in, say, Japanese jujutsu, or judo-it's just BJJ you have a beef with, right?