MD's know what they know, and don't know what they don't know
MD's have a purpose, and... a limit to what they know and can safely do for us. It's about win-win, everyone contributes what they are good at, and there is room for all.
In a world where we need to work together, each person has a purpose and what they are good at. When it comes to curing dis-ease, MD's fail severely.
Dr. Glidden an ND, speaks of the phenomena pretty clearly: