Yes, it's technically debt and I could have just paid but why take it out of an account paying me 5% to pay for 0% money? And when I was young and gullible I followed the crowd and got credit cards. I wizened up about 30 years ago.A car loan at 0% is still debt unless you pay it off at the end of the month. You may not pay interest, but it’s still debt.
As for the cards, it’s not a line, it’s a real way for disciplined young people to build up some credit. Not everyone wants to take out a car loan to build up credit.
How did you build up your credit score to allow a car loan at 0% if you don’t mind my asking?