Once interest rates drop below 5%, some other bad things happen. Companies performing badly use lines of credit supported by increased stock prices based on speculation value. If a company can't turn a 10% before taxes profit, stay away from the stock. It's too easy to pump the stock with PR, keep borrowing 2% money to meet operating costs, and you eventually find a crash.
The average bank card rate is about 20% and for store cards its about 30%. Very difficult to pay down balances with rates like that. But most consumers are oblivious to this fact, and quite frankly, don’t care. We are a very materialistic society where instant gratification is a high priority with consumers.