My general point would be that mistreating part of the population is a tool in a toolbox, and countries from all boards use it way more than we acknowledge.

We have democracies that either hang people on public places, pass eugenic laws, sentence gays to prison, or will engage in ethnic cleansing under official orders. Even in milder areas, prventing whole sections of the population from getting citizenship or limiting their reach (mass incarceration etc.) are well know levers that help a country be nice to its most vocal population while shutting down a whole section of the population. Those are readily available tools, whatever the political system.

And being well managed isn't abstract, you might be better off living in Monaco or Morocco, which are full fledge kingdoms, than a democracy like Nigeria for instance.