It's said that the long distance to North America was a key factor that greatly restricted the power of British Imperialism in America, and indirectly led to the success of the U.S. Revolution. When the orders from the top decision-makers in the U.K. mainland took months to arrive, efficiency was low.

I wonder whether the absence of FTL communication in the universe could be the ultimate physical guarantee of decentralization of political power (which is not possible on Earth) and the protection against universe-wide, total imperial powers.