Can controllers be completely replaced by the link function in a directive?

Question

I was reading through this article:

http://teropa.info/blog/2014/10/24/how-ive-improved-my-angular-apps-by-banning-ng-controller.html

Which proposes that controllers be integrated into directives like this in order to remove the need to ever use ng-controller:

angular.module('contestantEditor', [])
  .directive('cContestantEditorForm', function() {
    return {
      scope: {
        contestants: '='
      },
      templateUrl: 'contestant_editor.html',
      replace: true,
      controller: 'ContestantEditorFormCtrl',
      controllerAs: 'ctrl',
      bindToController: true
    };
  })
  .controller('ContestantEditorFormCtrl', function($scope) {

    this.contestant = {};

    this.save = function() {
      this.contestants.push(this.contestant);
      this.contestant = {};
    };

  });

In the comments, however, someone else proposed this solution:

angular.module('contestantEditor', [])
  .directive('cContestantEditorForm', function () {
    return {
      scope: {
        contestants: '='
      },
      templateUrl: 'contestant_editor.html',
      replace: true,
      link: function (scope) {
        scope.contestant = {};

        scope.save = function() {
          scope.contestants.push(scope.contestant);
          scope.contestant = {};
        };
      }
    };
  });

It achieves the exact same thing as the version with the controller without ever needing to make a controller. So I'm curious as to what the pros and cons of either method are versus writing angular traditionally with ng-controller, and whether controllers are even necessary by the end of it.

Here is the plunker for the first, and here is the second.

Answer 1

In directives, you should use link function whenever you can. Use controllers only when communication to other directives is needed.

You can find more about this discussion here. Specifically this best practice statement:

Best Practice: use controller when you want to expose an API to other directives. Otherwise use link.