That was an urban myth. The rooms were never designed to be pulled back out. Once in they were permanent. The modular allowed them to construct the entire Contemporary in 90 days (Lesser known, the Poly also was modular. And the off-site Court of Flags was also modular, rooms were built at Disney at trucked over).
Okay, well I completely used a terrible example but I'm glad that you brought this information to light. It's good to get things straightened out.