For someone that works a regular job, I agree. No business carrying a balance on a credit card. But for business owners, self-employed, they are vital. I like what my oldest son told his brother. Financially, he is a beast. Closed on his house a few days before he walked across the stage to get his diploma. Paid off his student loans in the first year. He uses nothing but credit cards, pays the balance off each month. Has a company card, gets to keep all the rewards and miles. Since he does a lot of international travel, business class always, he builds up an insane amount of rewards and miles.
So, at least once a month he is at the beach, in the mountains, taking a quick vacation, all paid for with rewards. He tells his brother, I get these rewards because of people like you, that carry a balance and pay interest, thanks.