Management is an often toxic mix between Strategy/SME/HR/Teacher/Therapist/Consultant/Punisher

Separate the functions out explicitly, as needed.

Often they're just corporate prison guards in organizations with bloated structures and antagonistic views of staff from an executive perspective.

Flatten your structures so the highest-level strategy is connected to your lowest paid staff. If you can't do this, then you have a toxic company that resembles prison labor and the whole thing deserves to fail.

More than two layers of management = a company that is bleeding money. More than one layer generally already means idiotic decisions are being made. I sort of hunger for an example of zero layers.

Yes but could they take the blame for that? A good portion of business decisions and activity is legal liability firewall engineering and maintenance. So promote someone you don't like to a manager and make them make cuts. Then resultant turnover and performance issues are their fault, not yours.