So the examples- "12 pounds of pressure" and "nose bone through the brain". The point isn't the myths. The point was that with very few exceptions, what most people believe on either side of either issue, is largely hearsay. Steve has actually looked at the skulls and talked to people with some expertise. Several notches more valid than any source I have.
So, if you have an opinion on either of these, yes or no, what was your source? Unless you have examined a skull or applied twelve pounds to your knee or lined up 100 people for precision teisho-zuhki practice at full force it is at best an opinion. These were softball questions, easy stuff.
Then we get into things that, if you are a martial artist, you have seen again and again and again. Things that if you examine have some pretty scary implications for what and how we teach.
Beginners are more dangerous than experts. More people are hurt by beginners than by senior students. There is a lot of scrambling to deny that one and the best 'reason' is control. First, control in this case doesn't equate exactly with functional precision. When an expert throws a full power punch and doesn't hurt you he has done one of two things- he has either aborted the power or missed. Pulling punches is missing, people! So it is a precision of failure. Perfect, flawless, failure. Years and years spent training to do the opposite of what you need to do if you ever really use this stuff.
You can argue that this is a dojo thing, that confidence makes the seniors more vulnerable in class but if it was 'for real' their years of polishing technique would surely prevail. I don't think 'for real' goes that way. This is anecdotal, but most practitioners have a story about a senior rank in their school getting badly beaten. That's interesting, for what it is worth... but every instructor I can think of has one and sometimes several stories about a student who was attacked (not went looking for trouble, not playing in a bar brawl, but ambushed) and did great with only one or two lessons. There are issues with this epistemologically- anecdotal, the sheer number of beginners versus the relatively few seniors, the fact that blackbelts getting beat and beginners prevailing make cooler stories than the other way around.
Still, you dodge this observation at your peril. No, you dodge it at your students peril. A certain percentage of everything is bullshit. How many of your training hours are doing nothing more than polishing a turd? And could that be the real reason that beginners are more likely to hurt you, because they still remember that it is about damage and haven't collected enough turds to polish?
Mindset. This comment got the most responses, and it is pretty solid. We know what a huge difference mindset can make. With even a little research, we know what some of the most effective mindsets are. Those are almost categorically opposite of the mindsets espoused in most of the martial arts I have seen (if they even address the question at all). Why? Could it be like bushido and chivalry, codes that arose in times when the need for warriors was fading and society wanted some way to leash the dogs they needed just a short time before? How much of training is less about empowering than about leashing?
This hits a lot of buttons, but some people don't even notice it when they slip into denial. I have a friend who is convinced that deep down he is a killer because once, when he was a child, he felt so much rage that he wanted to kill another kid. The uncontrollable feeling from long ago still holds him in awe. He has spent much of his life 'controlling his beast.' I hear the story differently. Everyone feels that way, most never act on it. Like most people he assumes that the greatest feeling he has ever felt must be as great as anyone has ever felt. Real killers are the ones who kill with far less emotional charge than that, who respond with violence to minor annoyance, let alone a seething rage. Many people feel this, "deep down I have a dark beast" and most who seek to control it are just putting a leash on a chihuahua.
I have a personal belief that animals, including humans, do things for reasons. In humans, the reason is not always what the person believes it to be. This loops back to fear management. For most people it is not important whether their martial training will help them to survive. They think it is, of course, but it is about managing the fear. It is more important to believe themselves strong than to be strong.
I think this is the motivation behind normally observant, intelligent people not noticing this stuff or excusing it when it happens. Probably also why these beliefs are so consistently reinforced- no one wants their world views rocked, especially when they have invested so much time and effort into the illusion.