Because individualism has died and everyone is yolked to their fellow man. This creates a world full of despair for most of the characters where no one reaches their potential and instead is forced to do whatever society tells them to do.
It is about Equality 7-2521 and his findings of individuality in apocolyptic times. Everyone is considered a "they." The word "I" is the Unmentionable word. A person talks of him or herself as "we",...