Not arguing for this credit scheme but in my personal case I use my credit card for everything and pay it off in full on the due date. The money sits in my savings account making a minuscule, but not zero, amount of interest while the card gives "cash back on purchases". Making a completely wild guess this nets me around $50 a month in "free" money.
Don't get me wrong, this isn't some plan to "hack the system" just my debit card expired and I never got around to getting a replacement so the credit card is all I have. But, free money is free money...