Heh, probably true, I'd have to say, on the 99% number.
On dangerous techniques.
A technique correctly executed using full force, speed, penetration, targeting, and rotation, is not safe. It will do what a bullet does, damage the target. Most live training or sparring takes one or two of certain ingredients out for safety.
In Martial Arts, guess what? It is targeting. Those kicks and punches are deliberately designed not to target effective zones of the human anatomy in a fashion that the force applied will break it. In joint locks, what is taken out is full force and penetration. Instead of snapping that guy's joint past 90 degrees, you are slowly pushing on it, deliberately applying pressure to produce a submission. To produce an injury, you snap it down with full force, including you body's mass, and it'll produce a distinct "reaction".
It is just a basic matter of safety that something has to be taken out of training physical moves. Force, penetration, targeting, speed. Something has to go from those. All techniques, done right, are too dangerous. Techniques that are not dangerous, probably should be discarded in favor of social de-escalation tools. Except in the case of police or bouncers, who sometimes have to physically subdue people without hurting them. Then again, if your friend is drunk, and you try that arm hold or what not on him, you should know before hand that drunk people have a 2-5 second gap in their response times. They don't feel the pain until then, so technically he could still hurt himself by struggling and popping his own shoulder joint out if you two aren't careful. Again, better to use social tools for social problems, and leave the dangerous stuff for dangerous situations.
On Brute Lee in MMA
The military really shouldn't be doing MMA, except for sports fun and morale boosts.
The MMA going to Marine Combatives training is an interesting case in point on that subject. Also combat AAR of some incidents for the Marines implicated a major weakness in MMA style training, especially a result of BJJ groundwork. Marines were standing around while a corporal and insurgent were on the ground, because BJJ 1 v 1 training had taken hold. Going over, putting a pistol to the target's head and blowing his brains out, obviously didn't occur to them. Nor did snapping the insurgent's neck from behind using a body roll. This incident resulted in a double kill because of training military personnel in MMA style training situations of 1 v 1.
Criticism of Sparring in Styles.
Train as you would fight. The more you sweat, the less you bleed. What this means is that the closer your training is to reality, the better results you will have. But you can't get too close to reality, else it will be reality. If a fight should be ended in 1-5 seconds. Your training should mimic that time scale. If you are training in sparring that takes longer. Guess what? You aren't training as you fight. That means your client better not remember something incorrect from their sparring in an actual fight. But can you guarantee that? They put hours into it. Their muscle memory will be it under adrenaline conditions.
"Avoid harming from full force contact"
That is correct. Sparring teaches people to fight under social conditions or rules. You do that to him, he does that to you. Real violence is about you getting injury on the target, not the target doing something to you. This ain't going to be a basketball game. This is more being the pool shark that never gives the other guy "his turn".
"I still am apprehensive it can be misapplied in training to develop bad habits, but I can see the benefits as well."
It is still misapplied, given the Black Belt anecdote. Both fights were social confrontations. Calling people out, trying to upgrade your status. The guy even left under a choke of a sort, because he was told "he won".
If your clients have gotten into such a situation, that's due to bad self-defense training period. I don't care who says otherwise. Black belt should have left the scene. His friends should have dragged him off if he didn't want to go.
There are too many incidents where people accidentally "fell" on concrete, busted their skull, and died from brain bleed, hematoma, or a cracked skull. This is like taking a gamble and if you win, you get to declare yourself a "strong man" and if you lose, you go to jail for 20 years (or get buried in the ground). Not exactly a good bet in my view.
The Black Belt had a freeze incident. He was worried about what the other guy was doing, so he kept blocking, then got to a point where he had to attack but he was too worried about defense. Sparring can increase a person's willingness to attack, but the mind isn't on the right track. The mind is still on this monkey politics of social competition. That will get you killed in asocial situations.
Sure, a guy could be fighting you, and you could be beating him down. Smashing his face on the ground or wall. Then he decides that he is getting himself beat down, so he pulls a gun and shoots you. And guess what the sparring trained person is going to do when that happens? He's going to freeze, having encountered something he wasn't trained for. The other guy may have started on you because he wanted to "fight" you, but then his motivations could shift to "kill you" and you wouldn't know until he did something about it, to you.