I have been an IT manager and IT director. I also (as a consultant) have helped companies find candidates in some of these positions. Especially for IT manager's/directors, but also true for some of the others, companies do not have a clue what they are looking for. I've had some embarrassing situations because a company laid out their "requirements", I identified and interviewed candidates based on those requirements. When the company management interviewed them - it was obvious they were looking for something else. They didn't understand their own requirements until they got some candidates in front of them. That is not an ideal situation. Sometimes "head hunters" are not very good at lining up requirements and candidates either.

A big part of the problem is that management often do not have a good idea of what people in these positions do. They have a generic and stereotypical idea of what they do, but very little about what skills it takes for people in these roles to be successful .