In many (most?) organisations, the career progression for specialists (geek, engineer, scientist, teacher, etc) is to become a manager. There are two small problems with this, though.
Firstly, not everyone wants to move away from their specialism and become a manager. Heck, they may even enjoy their current work.
Secondly, some people just aren't any good at being a manager. They may be the mutt's nuts in their field, but they may not be management material.
Unfortunately, our friends in HR don't understand this...