[I wrote that reply and then tried to corroborate it. Jung did not encourage "becoming your shadow" so I don't know where I got that from. In fact they treat the shadow like it's radioactive. I made an incorrect statement so I deleted it.]
When I learned the MBTI, I was in Jungian psychology class (which the types were loosely based on). It was my understanding that strong preferences indicated an unhealthy condition. I never believed the preferences were immutable.
In fact, the first thing I did was try to change all of my preferences to my shadow, which would make me an ESFJ, a counselor sort of person. My true type is INTP, which is the absent-minded professor type.
To this day, I embody more of my shadow than my primary.
Somewhere along the line, corporate culture (capitalism) got its hands on the enneagram and decided to use it for discrimination... I hate that they've ruined it, because it's so useful as a tool for analyzing yourself and others. And it can aid in communication too.