I've always liked the idea that reality is a shared consensus (at least as a fictional conceit. In real life, I'm aligned with Philip K. Dick: "Reality is that which, when you stop believing in it, doesn't go away."). My favorite take on this idea is in Sandman #18, "A Dream of a Thousand Cats." In that story, we learn that cats used to be bigger than humans and hunted us for sport. The humans gathered together and decided to simultaneously dream a new reality, in which they were the rulers of the world instead. It worked. Now a lone cat walks the Earth, trying to convince other cats to join his dream of bringing world back to the way it used to be. Of course, this will never work, cats being cats.
It's not tools or language that separate us from animals; it's stories. We alone are able to solidify our dreams and share them with each other. And, the scale on which we're able to do this in the modern age is staggering. The film touches on this quite a bit, opening with The Hobb's End Horror being mass-printed on an enormous maze of machinery and having Linda mention that Sutter Kane's novels are a billion dollar, global business. Kane's stories occupy and become real in millions of minds. This is powerful, even without considering its ability to warp the world.
You could also easily tie this back to Carpenter's prior film in his "apocalypse trilogy," Prince of Darkness. In that one, the Catholic Church creates a false story ("Christianity") in order to protect humanity from the true horror of the universe. Sutter Kane does the opposite. Stories used as weapons of war, both protecting and damn us. That's humanity's special power. The cats don't know what they're missing.
Watched: blu-ray from WB.