True, but the classes they took in engineering school were geared towards turning them into engineers. They may have ended up doing something else, but the classes they took were aimed at making them engineers.
Similarly, people with divinity degrees may or may not end up working in the area of their degrees. However, the goal of a degree in divinity for, say, a Lutheran is to become a Lutheran priest. So, the goal of said degree is to provide an education that will be used to benefit only a particular religious denomination. Now, if a Lutheran student was only studying religion or religious history in general, the goal of that degree would not be to provide a benefit to a specific religious denomination, though that might end up being the case.