Shock, horror! Well, I for one, believe this to be a true statement, but at the same time, I'm going to say, some karateka are very dangerous, they could and would, tear apart, 90% of attackers! So what's the difference between the two, ATTITUDE! When training, you are what you think, if you are thinking about cuddly teddy bears and cup cakes (just an example), you will be about as effective as teddy bear in a fight with a T Rex! If your attitude is strong and positive in the dojo, you are going to have a better chance in a real self defense situation.
When your karate is at full speed and power, you should practice like your life depends on each move, use some imagination, your karate can still be practiced safely, but when techniques become real, it takes on a whole new meaning.
Make it real.
When practicing kata (forms), kihon (basics) or kumite (sparring) at speed, when your strike hits the target, imagine what would really happen if you landed the blow with full force and no control, is it strong enough to hurt or even fell an opponent, it should be.
In the dojo, etiquette, control and discipline rule the day, in the street, they have no regard for your safety, they do not care if they kill you and they most definitely show no control or mercy.
I can't remember the exact words he used, but, the famous boxer, Mike Tyson, when he was world champion, said, 'They cannot hurt me, they cannot knock me out, I won't allow them to'.
In the martial arts, karate and self defence, that's the attitude to have.
Another Mike Tyson quote, 'Every shot was thrown with bad intentions'.
Some karateka naturally have this attitude, others need to train themselves to be like this, never give up, if you knock me down, I'm just going to get back up, I will not stop and when I hit you, I will hit with, as Mike Tyson says, 'bad intention'! So, to me, self defense is a state of mind, rather than a physical state of being, obviously the physical side is important, but all karateka have the physical side, don't they?