How in Hock?

Via Ezra Klein, I see that Karl Smith has come up with an interesting theory as to why consumer debt might not be as onerous as this chart seems to indicate.

But there's another, simpler reason why the consumer leverage problem has been wildly overstated. In 1980, the prime rate reached 21.5%; it's been going down pretty steadily since, and today it is at just a shade over 3%.  It turns out that Americans have gotten into debt largely because they could afford to.

Source: Federal Reserve Board.