This is eternal. The expert paves the way to understanding. Its only because of their expertise that they can simplify and explain it in a way that others can understand. They have a firm grasp of the concept. Understanding is not equal to expertise, just the first step.

I think there are too many times when people affect a tone of authority and expertise and hide their lack of understanding in verbiage and complexity while making excuses for their inability to explain it to the layman.