I mean it's "smart" and "efficient" but it's also fragile. The simplest way to manage your finances is to avoid debt wherever possible (especially consumer debt). Very hard to go into bankruptcy when you don't owe anyone anything!

The "smartest" way to manage your finances is to use credit cards that give you points and pay you back via a few hundred dollars worth of free flights a year. But there's a bunch of opportunity costs associated with pursuing that route, and a level of diligence that frankly most people do not have.

The best thing about debt is that it lets you move really really quickly - if you don't have $2k for that furniture set, you can just finance things and pay it off over 2 years. But that's the worst thing about debt as well - you now have a monthly obligation that's going to be a line item expense for the next 24 months. If you'd spent 12 months saving up for that furniture set and paid cash, the day you buy the goods is the day your financial obligations start and end.

I am not opposed to debt entirely, and think it can be a great strategic lever (I used a credit card to finance my initial move to America which has done wonders for my income and my career, far exceeding the interest costs that I paid). However I think for most consumer purposes it's less of a help and more of a hindrance. Take the new 84 month car loans. That's 7 years! That's a long time to assume that your life will have no material changes, or that nothing will go wrong.