Зачем нужен get prop()?

let user = { 
  name: "John", 
  surname: "Smith", 
 
  get fullName() { 
    return `${this.name} ${this.surname}`; 
  }, 
 
  set fullName(value) { 
    [this.name, this.surname] = value.split(" "); 
  } 
}; 
 
// set fullName is executed with the given value. 
user.fullName = "Alice Cooper"; 
 
alert(user.name); // Alice 
alert(user.surname); // Cooper