It hinges on the premise that superluminal travel is a limited resource sentient races are all trying to control and that alien races need to commit Ecocide in order to prevent competitive consumption. It also posits an eternal state of civil war between races, as communities diverge from one another geographically only to come back into conflict out of the same resource conflict. I don't think this pans out, even on Earth. Humans seem to have grown more passive over time, and more social. Our Dunbar Number is expanding to fit the needs of our increasingly interconnected world. Those bigger networks are rewarding their members with longer lifespans, healthier offspring, and an infectious ideology.

I'm more prone to adopt the theory that humans simply wouldn't recognize an alien if we saw one. We're peering out into the infinite abyss of space, looking for flying saucers and asteroid robots and big blinking Dyson Spheres. Has anyone bothered to check under the clouds of Jupiter? Or the oceans of Europa, even? If a spatial body was transmitting a superluminal radio signal, would we even know how to listen to it? We're like ants searching for other ants by waving our antenna at the moon.

Maybe Dark Forest Theory is correct and extraterrestrial life really is an All-Against-All war of attrition. Or maybe we're just a bunch of primitive assholes hanging out on the rural end of a galactic empire and we just can't see it for the glare of ten thousand suns.