Yes, but how often do they bother to explain this rise other than in some very vague way? And it isn't just feudalism. Look for example at Dune where not only is there a feudal system but the technology conveniently makes sword fighting once again a reasonable melee tactic. Additional evidence for the romantic nature is that almost invariably the stories are about people who happen to be nobles. So there's less thinking and focusing on how unpleasant feudalism is for the lower classes.

The only individual I've ever seen give a plausible set of explanations for the presence of feudal cultures is Bujold in her Vorkosigan books. But it is important to note that there there are many different governmental systems including dictatorships and anarcho-capitalist worlds and lots of other things. And she's very aware that feudalism absolutely sucks for the serfs.

I don't think that most of these writers are arriving at their societies by probabilistic extrapolation. Rather, they are just writing what they want their societies to have. (Incidentally, I suspect that many of these cultural and political norms are much more fragile than we like to think. There are likely large swaths of the space of political systems that we haven't even thought about. There might well be very stable systems that we haven't conceived of yet. Or there might be Markov chains of what systems are likely to transfer to other systems).