Over the course of a person's life, they will have many teachers. Academic teachers, spiritual teachers, parents, mentors, coaches, and (in all likelihood, since you're reading this) martial teachers.
There are some key differences, though, in the roles that a coach within a physical discipline and the roles that a teacher in a physical discipline will play throughout a person's development.
Emotional growth and the emotional well being of students is a subject very important to me and I believe one that more martial teachers should be concerned about. Many martial teachers are not. This is not a problem confined to either contemporary or traditional teachers, but rather some endemic in martial practice. Whether this is because martial arts instructors do not care to or simply do not know how to address the emotional needs of their students, I do not know, but the fact is that martial arts instructors are... bad at it, for the most part.
I was very lucky. My teacher was a reserved man in many instances, but always very careful to push students in the direction that they needed. The prideful were humbled, the self-deprecating encouraged, always with the same quiet but reassuring smile. I can count on two hands the times my master complimented me out right, but they are potentially the most important building blocks of my confidence today... those few moments where I knew my teacher had faith in my abilities.
Not all students of the martial arts are so lucky. I have learned from more than one teacher, though I call only one man my master, and I have not always been in such supportive environments. This has helped me pay attention to how many fighters (as well as people who pursue ANY rigorous physical discipline) have had their technique suffer because of doubt or self-deprecation beyond what is healthy in encouraging a student to push themselves.
As I meet more people from other, non-martial disciplines, I see how often this happens to other physical people and I've come to a conclusion: the difference is that other physical disciplines often have coaches not teachers and that martial arts instruction is moving more towards coaching and away from real teaching.
A coach focuses on the movement, the material aspects of training. A coach is less interested in the personhood of their students. They are not invested in the growth of their student beyond the student's ability to mimic... and so that is the best a coach can produce. Mimicry. A student, coached, cannot rise above the level of his instruction.
A teacher is invested in the student and as such has a stake in their growth. They rise and fall based on the success or failure of their pupil and place deep value in their emotional state. They want their student to grow beyond them: mentally, physically, and emotionally. It is the point of teaching.
I am tired of seeing students whose physicality is a thing of real, true, and intense beauty suffer because they do not know that they are believed in or trusted. Instructors take note and students, take the time to encourage and inspire those around you. We could all use it.