Paying off debts first doesn't seem like a first principal to me since there's contexts where that's not the right move. There's too much nuance to managing debt to generalize it that way I think. If the interest rate is below inflation would be the obvious example. All those people who bought houses or refinanced a few years ago are not better off paying down their debt first when they could be investing that money instead. I think a more defensible first principal would be something about paying down debt faster the higher the interest rate is on the loan.