It’s important to remember that - unless you work directly for the owner or an executive appointed by the board - they’re not your boss’ advocate either.
If the company is worth a shit, they don’t want bosses that abuse their power or make their subordinates miserable. Happy employees are productive employees.
We’ve rid ourselves of a few problem bosses that way. Of course, this only applies to legitimate issues. If a boss is causing people to quit, you’ve got a good case.