The little piece of plastic is not inherently evil, it's simply a temptation that most can't handle.

They are extended to entice spending which cannot be repaid in one months time. How else did the average debt become $15k?

Zero good comes from credit cards. I know, I've had them. I've done the miles thing, I've done the cash back rewards, I've done the old points for stuff system, I've tried them all. I currently have one credit card that is open. It was shredded. I keep it open because it keeps my checking account free with lots of bonus features and there are no annual fees.

But here's the problem with rewards lovers: the reward are too small. The Citi doublecash card is one of the best rated rewards cards out there. It gives you 2% back on every purchase.

The average American has less than 10% disposable income. The average American makes 51k/yr.
Even if they spend 100% of their disposable income on it, they get back $100. Now let's say they throw a couple of their bills on there (heating/electric/groceries) heating is ~600 yr. Electric is ~1300 and groceries are ~4000.

So total we have an additional 5900 which is a grand total of $11,000. They're getting back $220. And remember, they spent every drop of disposable income on a credit card and paid it off every month.

So for $220/year you're risking an awful lot, wagering your self control against massive interest rates and if you win, you get $220. If they win they'll get much more.