A republic is all about establishing a reasonably strong mean, back to which a succession of various administrations tends to revert.
Other forms of government allow for much higher variance. You might get a brilliant and benevolent monarch, for instance, but his son might turn out to be incompetent or tyrannical. In which case, sucks to be you. Hopefully the 30-year dice roll turns out better with the next heir.
Other forms of government allow for much higher variance. You might get a brilliant and benevolent monarch, for instance, but his son might turn out to be incompetent or tyrannical. In which case, sucks to be you. Hopefully the 30-year dice roll turns out better with the next heir.