That 'clever twist' has been in common use since the 1940s in science fiction.
I meant to say, it not present in recent works. At least not any I've seen or read.
Furthermore, no interstellar empire requires FTL. FTL is magic, and it's not at all necessary for a science fiction story. Refer to Alastair Reynold's 'Revelation Space' setting for a plausible space opera without FTL, and an interstellar society that works fine without it.
FTL is not magic. Our understanding of physics is primitive at best, there may very well be ways around that apparent barrier.
Conservation of energy. Action an reaction. - those are the laws to watch about. Not to mention breaking logic on a fundamental level.
And a interstealar empire without FTL would be pretty much impossible. There would be no way for a central government to control all of it. It would be a collection of independent planet-states at best. That's no empire.
Lastly, there is a big difference between tech in Sci-fi and magic (at least there should be in any sensible sci-fi). Good Sci-fi can make things plausible without actually breaking the known scientific laws. there are plenty of unproven theories out there and a lot of things that are possible, but not now.
Antimatter or fusion reactors for instance. Artificial gravity.
On the other hand you got "tech magic" like teleporters.
