Maybe that explains the popularity of Game of Thrones.
Fascism and Feudalism usually take over when the Empire falls.
The former works while some social and technological infrastructure remains. The latter takes over when the machines, or the slaves, can no longer be maintained.
They both flourish in dysfunctional environments and, of course, they do provide order! We all know how much "order" means to fascists, and feudal societies are very stable, if you don't mind a little local warfare every now and then..