Why would lack of empathy limit a density of autists in the userbase? Autism is more like a gravity, autists are attracted to each other because they believe to be next step in evolution and want to talk to each other. Therefore, the number of autists, once above the the CLA(Critical Level of Autism) given by repulsion of autists by normal users, the rise in autism of an online community becomes exponential. While this exponential growth has never been observed, it's believed by many theoreticians that this is because CLA has never been reached, but many fear that /prog/ is about to reach this this limit.
What happens afterwards is a mystery as of now. While the opportunity to study the exponential growth is scientifically very intriguing, there is a remote theoretical possibility that such density of autism in single online community could lead to a hypothetical Autistic Black Hole (A-Hole for short), where levels of autism are so large, that any normal user who even glances at the comments is immediately absorbed into the A-Hole and can never escape.