kyle- i believe what she was saying is that:
1. You don't HAVE to buy replacements filters from the manufacturer, you can just buy bulk filter media, and cut your own, which is cheaper and works just as good.
B. Carbon, although included in the filter replacements you buy, is NOT absolutly necessary to the well- being of your aquarium.
I will tell you this, i run a Marineland 350 and the replacements i buy come with carbon as well but i only buy replacements once, MAYBE twice a years, and i doubt my carbon lasts as long as my filters do, and my tank does just fine.