There is a bleak society in which there is very little diversity because, one way or the other, people are prevented from developing their own distinctiveness. There may, for example, be an oppressive government that persecutes deviants, or there may be some other social institution that makes people conform. It may be that people must conform in appearance, way of acting, way of thinking, or all three.

Examples:
In tz1959e5x17 "Number 12 Looks Just Like You", we saw a society wherein everyone upon reaching adulthood were required to undergo a surgical alteration to transform them into one of a limited preset of physically perfect models. The procedure clearly affects the mind as well, and is likely maintained by a remote government in order to maintain conformity and order.