I suspect you are wrong on the first part, at least for large technology companies. I do agree with the view of what is needed in practice to be a good leader.

I suspect you are wrong on the first part, at least for large technology companies. I do agree with the view of what is needed in practice to be a good leader. However, i think your assumption there is no need to do that is wrong. Take an area like the bay area - it has about 120k software engineers. This is not a small number. Even so, most companies the scale/size of Google, Apple, Facebook, etc have, at this point, interviewed 95+% of the bay area SWE population, and most (Apple is the exception here) had done so by the time they were ~10-12 years in existence. That is a very short time period to go through the available population, and the population does not grow that quickly. So even if there was zero rampup time, etc, none of which were true, they can't practically afford to churn people as quickly or as randomly as you suggest because they can't replace them fast enough except at very high cost. If you talk about something that has a much much larger available population, or companies with much smaller need it might be true.