Exactly. You have to read the words of those two with understanding of the world they lived in. They were -inspired- documents, NOT mormon golden plates, or the Koran that they think is exactly what god said, word for word.
Paul couldn’t imagine a Stalin and if he could, he would have never shrugged and said to do what they said. He woulda followed the words of Jesus and said sell your cloak and buy a sword had he known about them.
There is no biblical duty to obey a despotic leader.
Paul could imagine a Caligula, Claudius, or Nero, since he lived under all three. What he meant concerning being subject to authority is demonstrated by his own actions, which lead to his beheading.
Paul could not imagine a Stalin?
Hold on a minute.
Paul would have been quite aware of the murders committed by numerous foreign invaders. Ashurbanipal was the last great king of Assyria; take a look at what he did during his 38-year reign.
But there were many other totally murderous despots before the time of Paul.
A Stalin was totally comprehensible to people living in the first century AD.