But don’t good managers also cause turnover?
Of course. But it’s the good kind of turnover. People are advancing in their careers. Hell, they may even be taking on more responsibility for your company. (Internal recruitment!) It’s always hard to see someone leave a role they were good at, because it might mean more legit work for the manager, but …
Good managers create the kind of turnover that makes you say “Awwww, that employee is growing.” Bad managers create the kind of turnover that hits the bottom line.
So it ain’t rocket science on employee attrition
You want less of it? Train up your managers so they do something of value. Most of the admin work they do can be given to software. The people work? Not so much. They need to get their hands dirty there. In the simplest terms, they need to actually manage. That, and respecting employees + providing them a few perks or opportunities, is going to lower employee attrition.