Fun fact, at least for the PC version of this, there was like a quiz after the game launched you had to answer correctly in order to play it. Answers were in the book, but I failed many times being a young kid. I guess that was some sort of child safety mechanism.
Copy right protection, like boonhet said. I played many computer games that I had to copy the instruction manual to play. Might and Magic 3 was like "what is the 4 word of the 11th line of page 8?" And if you don't get that right then you can't play. Civilization had similar prompts, but it let you play a little bit and just hurt your progress if you didn't answer their questions about the civilization skill tree.