Collection seems chainable in the Chainable API example

[ravenjam]

In Chainable API example I saw this:

var collection = new Backbone.Collection([
  { name: 'Tim', age: 5 },
  { name: 'Ida', age: 26 },
  { name: 'Rob', age: 55 }
]);

var filteredNames = collection.chain() // start chain, returns wrapper around collection's models
  .filter(function(item) { return item.get('age') > 10; }) // returns wrapped array excluding Tim
  .map(function(item) { return item.get('name'); }) // returns wrapped array containing remaining names
  .value(); // terminates the chain and returns the resulting array

console.log(filteredNames); // logs: ['Ida', 'Rob']

Therefore I tested to just use the collection without the chain() method. It seems that it worked well. I ran this in the console:

var collection = new Backbone.Collection([
  { name: 'Tim', age: 5 },
  { name: 'Ida', age: 26 },
  { name: 'Rob', age: 55 }
]);

collection
  .filter(function(item) { return item.get('age') > 10; })
  .map(function(item) { return item.get('name'); }) ;

and it returns ['Ida', 'Rob'].

I'm wondering why? It seems that the chain() method is not necessary? Thanks!