Been a while since I wrote an essay . Trying to provide a point for your counterpoint, not establish dogma.
Human, monkey and lizard.
There are thee layers in your brain each piled on top of another. Oldest one is the cerebellum i.e. the reptilian brain.
On top of the cerebellum there is the limbic or the monkey brain handling the emotions and peer relations.
The latest addition is the cortex which capable of processing abstract concepts and long term planning.
The interesting thing is that each that the cerebellum is happily chugging along exactly the same as it did in the jurassic era. any new functionality is just a hack added on top of that, nothing is removed, just added. When you flip someone off your cerebellum tells your all fingers "ball up" and your limbic system adds "..except middle finger, you extend". When you see a woman you really like its your cerebellum screaming "Fertile female without genetic defects, have sex with her now!!!", your limbic system adds "to achieve this demonstrate affluency and your desirability as a mate" and your cortex enables you to say hello and buy her a drink.
So in essence you are three things piled on top of one another. Human, monkey and a lizard.
Human will not as much fight as use force to achieve goals which is long term or abstract such as money or honor. This is what makes humans scary, you may say you are "fighting" rats, but you are actually exterminating them. Human is able to coldly put a bullet through someones head from 600 meters. As human you accept artificial constraints like "no biological weapons" or "no biting".
When fighter trains for months, formulates staregies and fights for goals which are not directly related to immediate survival, mating or status, thats very human action.
Monkey will fight for status. Monkey has wetwired (i.e. genetic) constraints which will prevent it seriously harming a member of the same species. Broken bones yes, broken skull no. Monkey also has wetwired pattern for using physical violence, which is codified by Patrick McCarthy as HAPV-theory.
There is much overlap between human and monkey, the cortex capable of human thought is only about 50 000 years old so its natural that monkey jumps out every now and then. Computer geeks have term "alfa nerd" which jokingly acknowledges that even among the people who (supposedly) smartest around, still fall back monkey behaviour when dealing with other monkeys especially when women are around.
Monkey brain diverged from lizard around 200 million years ago and lizard will still come out, usually in situations where direct survival is at stake but lizard can override human and monkey if your body chemistry is altered either by illness or mind altering substances or when human and monkey simply run out of answers e.g. in continued high stress. When you don't know what else to do you either eat, kill f*ck or walk away.
Lizard fightin is blind aggression using anything it can and without any constraints with everything your body can produce. Hence there are stories of men fighting off a bear or women lifting cars from top of their children.
So what has this to do with Karate?
I claim that martial arts in general and Karate in particular is human trying to deal with the monkey and the lizard. You are trying to circumvent the monkeys wetwired violence routines and lizards blind aggression to more efficient use of force. To achieve this there are no other ways than endles repetition of the movements, which we have come to call kata and constant conditioning in situations which mimic the monkey and the lizard may jump out. Relative merits of different fighting systems are a point which we debated endlessly, but the actual training, repetition and pavlovian conditioning to situations are what make them effective.
This is also makes the fundamental difference between sport and true martial art [tm]. While you may be formidable fighter as long as you are able to hang on to your cortex functions, even professional fighters have a tendency to grab and swing a haymaker once the monkey takes control. The only way to ensure that the aquired reflex is stronger than the one we are born with is constant condtitioning.