Doesn't it seem like one of the missing measurements for directors/VPs should be "amount of disappearing expertise"?

you would think, but then you'd have to actually do something to retain talent instead of hiring whoever you can whos cheaper and has no idea how any part of the software or or company works. But of course the comp/hr team never see it that way.

More the old guard leaves, the more of the old guard that leaves. Then who is left to train the new people?

Fun fact: very few directors or VPs at Ubiquiti. Very flat organization

Often times churn is rewarded because it can keep salaries lower.

The directors and VPs quit, also.