Interesting thread.
It opens up a discussion on what is "efffective" in a fight, and what is not.
Yes, some people will give up the ghost if they get poked in the eye. Some will if they receive a sickening blow to the kidneys. On and on it goes. And, of course, some will give up if you give them a mean stare and say "I'm going to hurt you." -

But, do you know what? The guys we should fear most are the ones who won't stop coming at you because of any kind of pain. There are even cases of people being stabbed, or even shot, without even realising it until after the event. Even if you inflict mortal wounds, a dying man can still kill you before he realises he lost. That's partly why Hock tells you to draw attention to the bad guys wounds in the Ground fighting tapes!
The only real way to win with any certainty is either a kill (a quick one!)or a knock out.
To labour the point - stab Mike Tyson in the head and he may still be able to eat your throat. Knock him out and he can't.
Now, of course that is much easier sad than done. But nobody with a brain will tell you that fighting is easy! The Tysons of this world don't go down easy, and Pee Wee Herman is always going to struggle against him.
But there's a million logical falacies in the martial arts, and one of them is that if a small man cannot do a technique with any real power (like a knock out blow), then give him a technique that doesn't need size (like an eye jab) and this will give him a chance. It's like "its ok to be small and weak. You can still win"
But, without great luck, that is nonsense. The bigger and stronger you are, the better chance you have. That's just a fact. If you don't think so then imagine you could magically grow 30lbs of functional muscle over night. You get more weight and more strength, much more. Are you going to be a better fighter in the morning, or a worse fighter? Not too hard to figure out, is it?
Another analogy, this time re driving. We have the skill (the driver himself) and the tool (the car). This represents the fighters skill.... with his tool being his body.
You could put the World Formula 1 champion in a Vauxhall Corsa 1.1, and someone who has only just passed his test in a Porsche. The odds are stacked massively in favour of the beginner - because of the tool he gets to employ.
You need the skills of course, but you still need the tools. You need to produce as good a body for fighting as you can, and that includes size and strength.
You jab away at eyes all you want. Like I said, sometimes people will throw in the towel. But those out there who are the real threat won't.
And those small vulnerable students? Yes! Give them the skills! But, if they won't or can't turn their bodies into sizeable fighting machines, lets not kid ourselves that teaching them to strike some so called vulnerable area is going to equalise things for them. They're just less likely to win - fact.
Now there are always going to be some exceptions. Even a dwarf can become great at basketball..... But see how much better he is if he wakes up next morning and is 7 feet tall.