It's a disadvantage our system or any system where the population votes in the leaders and many can be so easily tricked. A really great dictator who does everything right or most things right, if he is benevolent and not harsh, is most effective and gets you the best result. The problem is, for those types of government systems it will be rare if not impossible for someone to be such a great leader and it will in turn produce a much worse subsequent dictators with absolute power, who will erase and subtract from what such a previous great leader has achieved.