True D.I. vs service locator.

I messed around with Pimple a bit just out of curiosity. My question to you so I can  understand what exactly you are looking for is, how is attaching objects to the Pimple Container and passing it into the class any different than attaching the objects to the CodeIgniter "Super Object" and calling it directly ( get_instance()->my_library->do_work() ?) I understand for testing sending in mocks (when using DI) is a little easier but, it seems the CodeIgniter team has unit testing working regardless. Besides unit testing what other benefits am I not understanding?

As a side note:
I assume most dev's like me add a ci() function as a shortened version of the get_instance() function

DMyers

https://github.com/ProjectOrangeBox / https://github.com/dmyers2004