You can use bitcoin to buy a wide variety of items directly for bitcoin, and everything indirectly through exchanges and buying Gift Cards and reward accounts from Gyft, Hence can actually buy everything from Walmart to Amazon indirectly.
The problematic being discussed in the thread is not about the range of goods you can get with bitcoin, which is very wide, it is the speed at which you can do so, while buying something in amazon does not require extreme speed, something as simple as buying a coffee with bitcoin is very slow.