What do you mean? Why it's separate from the thing that `this._fetch(ajaxOptions)` returns? That's because the AJAX deferreds only resolve with the AJAX data. We need to resolve with that data plus the resource (here the resource *collection*).

Or do you mean why it's separate from what `this.fetched()` returns? I'm not really sure what the point of `fetched()` is, but it never seems to get reset. That is, if you fetch, then expire, then fetch a resource, `resource.fetched()` will always return the same deferred even while the resource is being fetched the second time.