Why use OOP constructs in an AngularJS application?

Question

Angular

I came across one application and it interested me. As far as I understand, OOP principles are used in AngularJS under the hood, but here's why and for what purpose they should be used in service controllers and directives. I would be very grateful if someone could sensibly comment on the following code snippets:
1. Factory:

fcatory('Fac', function () {
 return new Contr();
  function Constr () {
     this.tratata = 123;
   }
  Constr.prototype.fu = function () {}
})

2 Directive:

.directive('myDirective', function () {
  function MyController () {
  this.x = 1231234;
 }
  MyController.prototype.fu = function () {}
 function Template () {
// тут логика конструктора
}
    return {
          restrict: E,
          *****,
          template: new Template();
          controller: function($scope, $element, $attrs) {
          var myController = new MyController($scope, $element, $attrs);
          $scope._myController = myController;
         }
}
})

What is the advantage of using this approach in an AngularJS application, is there any?