That's interesting and sounds like a hole in my knowledge of history. I'm curious, were those monarchies actually dictatorships? The UK still has a monarch, but it's not a dictatorship.
There are basically two kinds of monarchies, absolutist - the monarch has absolute power, so it is actually a hereditary dictatorship - and constitutional monarchy, which is mostly what you see today in the UK, Netherlands, Belgium, Spain etc.
Going further back in the history, some feudal monarchies were actually not absolutist in the sense the king had to manage various factions of landowners, clergy, etc (so-called Estates) or even share power with them. So it all depended on the relative power of the monarch and others in the society.
