I was not expecting such a Machiavelic answer, but yes, your explanation looks quite possible. Indeed, it is possible that the expertise ceiling that goes on a lot of companies is due to misaligned incentives (plus some dishonesty) for management. That seems worth taking a better look.

> It's quite believable to me that being seen to cut down a few tall poppies might have a positive impact on (mean) employee happiness in some cases.

This again... I dread to imagine going through the day around people that think like this. But people that think like this exist, and I imagine they concentrate somewhere. If some place makes them happy (and everybody else unhappy as a consequence), you'll probably find them there. This is really believable.