Why would the ability to create realistic sketches make a person a more competent designer?

The ability to create realistic sketches is a person who is considered to be a competent designer because they were able to represent objects in real life with the use of their sketches in a way that this will affect their designs to be more enhance as it is efficient and more effective compared to sketches that does not depict more realistically. This will make other people see a better picture and understand these sketches, having to establish a more clear communication.