I don't think that's quite fair. While the quote oversimplifies it, you too are oversimplifying it. If the boots situation existed your planned boots-loan would never work.
Because poor people are high-risk loans, you'd need to put a significant risk factor on that boots loan if you ever hoped to break even (there's a reason credit cards charge 20+% interest). So now the $100 boots are $130 or more.
Additionally, nobody not already in heaps of debt would ever take the loan, because people hawking predatory loans and money-for-nothing schemes are a dime a dozen in poor parts of cities (cash4gold! payday loans!) and those who don't lean quickly to ignore them all get screwed.
Finally, you're ignoring the psychological aversion to taking on debt, even if it's for the best. Even among fairly well-to-do university students the concept of business leverage seems to come as a bit of a shock, and takes a fair bit of explaining - "But why would you deliberately go into debt?". Imagine trying to explain to somebody below the poverty line that the boots are worth going into debt for!