I know that most of what he said is in fact the core of effective hacking. I was a friend of Capt. Crunch, John Draper, in the early 70’s and stayed in touch with him well into the 90’s.
Crunch was the most famous phone freak of his day and later transferred his skills to designing computer software.
I spent many hours listening to Crunch describe his exploits including many hacks into the FBI and the police who were constantly hounding him. Crunch called most of his technology ‘social engineering’. A phrase also used by Mitnick. The reason is that much of the time he had to get access to telephone lines or computers by phoning someone in a key position and getting the information needed for access.
"Mary, this is Jim in accounting. I know (your boss) Sam is on vacation, but before he left he said you would have the current password for his travel accounts. Was it 45446?" " No, its 45422."
That is precisely what Kevin Mitnick was suggesting is the secret to hacking.