As far as a lack of technical knowledge in the United 747 NRT incident, UAL at the time was under a court ordered settlement of an EEOC lawsuit to promote hiring from a broader demographic.
It was argued, for example, that giving a simulator evaluation in an airliner cockpit would be unfair to folks who had no experience in large aircraft. So United switched to a little Frasca desktop general aviation trainer for the sim eval at the old Stapleton airport.
Technical tests were eliminated in hiring and training since they were deemed biased against people with poor technical skills.
Anyway, for better or worse, much of the traditional systems knowledge was removed from the training and manuals.
And, I would observe that this trend has continued in the decades since.
In the U.S. the traditional oral exam to test systems knowledge has been replaced in many CQ training programs by progressive computerized training.
Even if you do know the aircraft systems, using that knowledge to troubleshoot an abnormality not in the book is frowned upon unless you get a phone patch to a subject matter expert and 'reach consensus on the best course of action'.
I probably sound somewhat nostalgic for the days of the flight engineer. Even as a pilot sitting the panel I was trained by true professionals. I knew the systems far better than I do today sitting in the left seat. And, training was so thorough that the oral and checkride were anticlimactic.
Now, training consists of checking boxes of the latest laundry list of items the feds want, rushing through the sim, pencil whipping some stuff to get out on time and breathing a sigh of relief that I don't have to do this again for another year.
