Notice how conveniently we are placed, far away from any other interesting objects in our galaxy. If you were designing a simulation, what would you do to keep your simulated beings guessing about the rest of the universe? You would make everything interesting inaccessible, and you would not attempt to simulate other species communicating, because that opens a can of worms where you now have to simulate an entire other civilization (or 3). better to just leave it empty and us wondering.

The emptiness (both physical and with respect to life and technology) is like the wall at the end of "The Truman Show" ("Free Guy", "Thirteenth Floor", "Dark City") -- the arbitrary end of our simulated universe, beyond which there is just wireframe or a painted backdrop.