A quick look at what making objects without using this might look like. I'm particularly interested in keeping methods decoupled so that they can be put into their own modules and easily tested. This leads to a pseudo-this object (called context here) to give methods access to shared data.

thislessFactory.js

// Methods will be bound. This allows them to be public or private
// later on without needing `this`. These can be required in etc.
function addToCounterMixin(context, num) {
  context.counter += num;
}

// Use this to proxy a field on from one object to another.
function proxy(context, obj, fieldName) {
  Object.defineProperty(obj, fieldName, {
    set: function (val) {
      context[fieldName] = val;
    },
    get: function () {
      return context[fieldName];
    },
    enumerable: true
  });
}

// This is what replaces a constructor.
function makeObj() {
  // Context holds all data that methods may need access to.
  var context = {
    counter: 0
  };
  
  // Bind methods to a context.
  var obj = {
    addToCounter: addToCounterMixin.bind(null, context)
  };
  
  // Get and set counter on internal context. Probably best avoided.
  proxy(context, obj, 'counter');
  
  return obj;
}