>> Hmmmm... spending money you don't have is how modern economies work, to a great extent. Companies take out loans to fund investment when cost of capital makes sense. People take out mortgages to buy homes.

I think it's worth distinguishing between different kinds of debt here. The article is discussing consumer debt (caused by consumption). The debt you are referring to is capital-debt, ie debt incurred to purchase an asset (which could be resold) or used to build an income.

Consumer debt is typically bad, and asset debt is typically good

But your point is not wrong. Western economies are largely fueled by consumer debt. If consumers all spent according to their means, and saved as much as they could, the effects on the "economy" (which is literally the "movement of money") would be devastating.