Interest rates, late fees, convenience charges, insurance fees, etc. all help churn revenue for credit card companies, and in doing so increase the debt for people that may have realized they got in too far - but too late. When you're behind, the last thing you need is to pay interest on an outstanding balance that you're not continuing to purchase against.
Many people accumulate debt because they are in jobs that do not adequately pay their workers. Alongside inadequate pay is a rise in the cost of living which people cannot simply keep up with. The blame lies in the companies who do not pay their staff what they need to survive.
I do not think the credit card companies are to blame because when a person signs up for a credit card they sign an agreement that details the terms and conditions. If someone is in debt by using a credit card, that is their own irresponsibility and they are the ones to blame. I think 1 in 3 US adults being in debt is more likely due to student loans and medical bills than credit cards.
I think consumers are to blame and the culture that promotes consumerism even when they know that people don't have the means. We are obsessed with technology and having access to the newest things all the while half of all Americans don't save for retirement. The credit card companies are a tool, but if they didn't exist people would still get themselves in debt.