Totally false and completely naive.
Most knowledge and know-how is not explicit - they are often learned.
For example - suppose you worked at Nuance, and helped develop their new AI/Neural Network speech recognition system. Everything you know about Speech + AI you learned from them, in that language specific setting.
If you went to work on Google's new Speech Recognition, which is AI-based - it would basically be impossible not to pass on know how and relevant knowledge. The application-specific skills are basically IP.