>democracies
Firstly, you must realize that the majority of people are born with a default mode of operation -their human instincts and emotions.
It takes education and suppression of these in order to refine yourself.
tl;dr Billions aren't born with Meditations by Marcus Aurelius already implanted in their brains.
This means once you educate yourself, you have become an educated minority. It is then your duty to rule over those who are uneducated relative to you because of natural hiearchy.
You may ask
>But isn't democracy then A-OK?
No, because educated men have better judgement than these uneducated people I spoke of earlier. The latter are easily swayed and influenced, while the former are less so.
Democracies are just tyrannies of the majority who in reality are controlled by who can control the people the best using manipulation. Humans will always be manipulated, because as I said, they are born with a default mode of operation.
>Republics
Men form tribal groups all the time. The elite form secret societies, fraternities, etc. which act as aristocratic factions. They then groom their politicians to pretend to act in the interest of the country when their actual loyalty lies with their faction.
This then falls back onto he who can manipulate the most people. He is then seen as unaccountable because it's the people's fault, never the manipulator's fault.
With a monarch, you have a young man trained since childhood to manipulate and rule, but for one faction - the royal family.
Out of all these secret factions, he's given the loudest voice in the room and can write all talking points for the aristocrats underneath him.
The monarch is also easily held accountable compared to a bureaucracy.