I've seen it happen way too many times. Usually it's over the sort of stupid politics and immaturity that characterizes most martial arts organizations. It's particularly common when one guy is in charge of a style and has sole authority over credentials. Teacher and student have a falling out. The teacher de-ranks the student usually with denials that the student ever really learned much of anything.
It's particularly common in Filipino and Indonesian martial arts although I've seen it in various styles of Kenpo and Kajukenbo as well as Chinese MA and even Japanese koryu. These days some teaching certificates come with an expiration date. If you don't renew (and keep on the Head Guy's good side, and keep paying, and know what to kiss and when) you are no longer an instructor after a certain amount of time. If your teacher breaks with the organization you are given the choice of completely abandoning him or being cast into outer darkness.
So no. It's not uncommon. These days it seems like it's barely unusual.
It's particularly common in Filipino and Indonesian martial arts although I've seen it in various styles of Kenpo and Kajukenbo as well as Chinese MA and even Japanese koryu. These days some teaching certificates come with an expiration date. If you don't renew (and keep on the Head Guy's good side, and keep paying, and know what to kiss and when) you are no longer an instructor after a certain amount of time. If your teacher breaks with the organization you are given the choice of completely abandoning him or being cast into outer darkness.
So no. It's not uncommon. These days it seems like it's barely unusual.