There are some extraordinary situations where it really does make sense: an example I read on HN a long time ago was the first cellular radio engineers that App

There are some extraordinary situations where it really does make sense: an example I read on HN a long time ago was the first cellular radio engineers that Apple hired before building the iPhone. The simple fact that they interviewed for a job might have been under an NDA. This desire to protect secrets probably gets extrapolated and trickles down to every technical candidate.