He explained it in the article, though it was easy to miss. If you need a large amount of cash for something, and a lot of smaller figures coming in, you pay for everything with revolving debt and let your receivables stack up in a bank account. It's one way to save up money for a down payment on real estate, maybe the only way if your lifestyle is close to your income.
That's why Debt-to-Income ratio is a thing. If you're someone who's typically adverse to debt but willing to make an exception in the case of real estate, and you're living close to your means (while renting), then it can seem to make sense to get your necessary down payment (plus closing costs etc.) through revolving debt. As long as your DTI remains below the cutoff, lenders are happy to let you do it.
