Something that doesn't put borders on the mind to box it in. Out of the Box Thinking, i.e.
EDIT: As for "why"... I only have a limited time on this planet and I'm not going to spend it on inefficient ways of learning. I'm not a believer in the phrase that "it doesn't matter how you got to a destination, so long as the destination is the same". Death is a destination all mortals share, whether they are an organic life on a planet or the stars in the heavens. But how they "get there" defines the nature of their existence. It also matters if a person gets the right answer on a test because they "guessed" or because they "knew". I'd prefer not to "guess".
When I was younger and felt the hot blood of impatience keenly, I cared only about achieving results. The faster I got to the end, the better. That is a benefit of ambition and determination, as well as pragmatism, but the more I learn, the more I realized that the end result becomes meaningless if I took the wrong path to it. The Way and the Path must be correct or the end result becomes an illusion, a mirage. Something people fooled themselves into thinking was worth it.
There are many ways to nitpick things and say that someone is doing something wrong. This often happens when our goals conflict and are mutually exclusive. But when our final destination is the same, it seems very pointless to waste energy arguing about trivial methods and means. Yet, paradoxically, that kind of argument and contention is required to determine the Way. Because not every "method" will achieve the goal. Or to borrow a pattern from quantum mechanics, every new path leads to a new destination, even though they look like they are all the same. The only true equality comes from two particles quantum entangled, being of the same identity. The fact that in one world a butterfly flapped its wings and a hurricane happened, and in another world a butterfly waited and the hurricane didn't happen, is very important.
If the destination of human life is all the same, death, then it becomes critically important what we choose to do before then. And if each individual has their own destination by feat of their own choices, then it becomes even more important that each choose wisely.
While I won't prejudge their choice (of styles and martial arts) to be wrong, people often try to avoid making decisions for themselves by dumping it on someone else. They find a teacher or a master to follow, because they are not confident in their own abilities. Eventually every child must set off on their own. Eventually. The sooner people learn to think for themselves, without copying the ideas and thoughts of others, the sooner they will be prepared to make their own journey.
"To be honest I do not think whether they live or die is the matter at hand. Life is not always better than death. It is not that simple. Living and being made to live are very different things. What matters is what the person chooses of their own free will. Whether or not it can be achieved or how difficult it is.
I want you to think about this: imagine if what matters most to you was taken away against your will. If that is indeed worth less than your life" -M, Meiya
"I would rather die having spoken in my manner, than speak in your manner and live. For neither in war nor yet in law ought any man use every way of escaping death. For often in battle there is no doubt that if a man will throw away his arms, and fall on his knees before his pursuers, he may escape death, if a man is willing to say or do anything. The difficulty, my friends, is not in avoiding death, but in avoiding unrighteousness; for that runs deeper than death."-Apology Plato/Socrates
And for those amongst us that have not as of yet considered life and death in the context of choosing "martial arts", perhaps this is the time to make a change.