So we panelists hashed out how badly they do it, with the lack of the structures of vassals and all that. And one panelist objected that it was a response to a very specific set of circumstances and another said that it has, actually, arisen in other situations.
About half way through it lurched on to the topic of governmental systems that are atypical of fantasy. I mentioned the Shire, which is a Kropotkin-type anarchy and populated by hobbits, who are much better than humans and complacent unimaginative stick-in-the-muds, which is why it works.
The Empire and a panelist complained about how simple Empires are, with the Emperor, who has free time, and a few officials. Especially Galactic Empires. (I recommended the Ciaphas Cain and Gaunt's Ghosts series to him afterward, and he observed that games often do it better because the gamers expected it. True, and the better Warhammer 40000 tie-in use it!)
The description asked if Marxism could work in a fantasy world, I said it didn't work in the real world, and another panelist said it could only work in a fantasy world, and thus we exhausted that in two sentences.
Update: 'cause I remembered something important -- we also riffed on how much you should go into. Absolute monarchs without vast bureaucracies mean you just have to convince the king, rather than all the log rolling you would have to do in, say, the US. If the politics is not central to the story, that may be just what the writer needs to keep the focus where it belongs for that story -- off the politics.