There's a silly phenomenon among people who share similar interests, like martial arts. It is the feeling that they learned the purest and most correct version ever taught based on their lineage or instructor, but even more so, because they really really believe that they are the most correct exponent and god's gift to martial arts. Now yes, lineage and qualified instructors do better your chances of learning things more efficiently or effectively, but then again how well did you interpret their teachings?
Simply put, every school, every instructor will teach things differently whether they try to or not. Language and body movement facilitate this, how they word their descriptions, where they emphasize their movements, and what speed it is performed. Not to mention, an instructor can place a specific emphasis on a detail pertaining to that particular student, that eventually the student shares and perpetuates to their own students. The cycle continues, the effect becomes much greater, and the further the art deviates from the original teaching.
An evolution of the art is constant, and I try to be optimistic that the evolution is positive, especially since we have better ways to safely test and understand the art and techniques with protective gear and controlled sparring sessions. However, it doesn't change the fact that the art is changing and I would rather embrace the differences than cut each other down because of from whom or when they learned it.
I dunno, that's just how I was taught.