Well, the assertion of the report in the main article is that, in essence, the economy revolves around debt, in one form or another. Remember, debt and investment are two sides of the same coin: you can't invest in something without someone else ultimately owing you money (i.e., being in your debt). And U.S. treasury bills are an investment/debt instrument that's hugely important to a lot of people and institutions, particularly the financial institutions that form the base for most of the economy.

Another way to look at it is that it's not just government debt that's important; there have to be some people who owe other people money or the economy doesn't function. The normal process of business institution-building is founded on the idea of loaning money (again, we usually call this "investment," but it's debt at its base). A good way to think about it is that if you are debt free, that's good for you, but if everyone were debt free, we'd still be living in an incredibly primitive economy.