Traditional corporate IT or MIS departments were based on scarcity. Hardware was very expensive, unreliable and hard to use. Computer networking required vendor specialists, each of whom went to school at length to learn how to point fingers convincingly at the specialists from other vendors for a minimum number of hours or days before getting down to fixing their own problems. Of course, this is an ideal. A major problem with such IT professionals is survival.
Many corporations view technical people in a schizoid manner.
The old IT mentality is in part a survival adaptation which helps perpetuate the environment which necessitated the adaptation. Computer people are not an intrinsic part of the culture of, say, large manufacturers or distribution firms. They have been viewed historically as a necessary cost more than as enablers of critical business activities. This led IT professionals to view their careers from the standpoint of personal technical development for steadily increasing marketability and a succession of different employers, and not as staffers who would enjoy progressively greater trust from and responsibilities to their employers. This would then explain how some such professionals would fail to see the utility in products such as the Macintosh, which can perform the full range of functions but which require far less support from technical personnel.