There is a common sense though in such uncompromising protection of your ideas. Especially if you’re running Apple Inc., that builds its marketing strategy around intrigue and conspiracy. Or if you’re investing billions of dollars into R&D. And truth be told no one would violate confidentiality agreement signed with such companies.
On the other hand ideas worth nothing without execution. If you’re building a company, you need to multiply two things: idea & execution. From such point of view, additional precautions just gain you a little time and initiative against competitors. Specifically, by requiring a signed NDA you may win additional time before your rivals enter the market.