Consumer Utility Maximization equivalent of economies of scope Economies of scope captures the idea of having efficiency in variety. I've come across this idea only in producer theory to capture the idea that companies may benefit from their ability to reduce cost of production through horizontal or vertical integration.

Quoting Micheal Carter from his book Foundations of Mathematical Economics,


  The production technology displays economies of joint production or economies of scope at y  y1; y2; . . . ; ym
  if the total cost of producing all the outputs separately is greater than the cost of producing the outputs jointly


Is there a consumer theory equivalent of the idea of economies of scope?
Nothing explicit, but I think that there is no real need for a special consumer theory...

If we see diversity as similar yet not identical products, for example red and yellow shirts, then for the theory to hold, you should have specific demands for yellow shirts and red shirts

We touch marketing basics, but this is the core element of differentiation:
Markets split into sub-markets until an imperfectly imitable product is being made, then a premium can be collected on
A premium labeled red shirt for example