The credit card might be one of the major contributors to the problems in the US economy. It gives people too much freedom with spending than ends up biting them in the butt later because they have to pay it all back and then interest will start to pile up as well.
The financial crisis was caused by banks taking risks and using complicated derivatives that no one understood. Credit cards were not a large contributor to the financial crisis. Deregulation of the mortgage market and bad policies by banks were the major cause for all of the problems in the banking system.