Are you asserting that those five turn over a majority of their mid-career engineers annually? That's the only way I see the tens of thousands number being accurate.
As for "mere mortals", I think most of us realize these companies hire them. Hell, I've been interviewing for my company a lot recently and a number of the people from those companies have been underwhelming at best (some to the point of causing me to wonder how they got hired there and I didn't). The issue is that many of us have soured on the random bullshit in their processes and have decided to stop throwing ourselves at it. I think it is a disservice to the up-and-coming not to acknowledge that and for them to realize it is "realistic" in a similar way that hitting a number in roulette is.