My experience, unfortunately, is that good managers like you seem to be don't last long. They get replaced by manage-up sleazeballs who'll never, ever protect the people beneath them because it's not game-theoretically optimal.

The thing is, executives measure themselves by how quickly they get promoted into the next role, so no one cares that good management might reduce turnover in the next 2-3 years--in fact, the executive mindset is that it could just as easily increase turnover (what if we invest in their careers, and they leave?)