This is factually incorrect, in addition to being bad advice. You take on debt when the net present utility of the purchase is greater than the price of the debt.
Here's a simple example to illustrate: you have an interview tomorrow, and you want to buy a suit to be sure you are appropriately dressed for it. The net-present-utility of the suit is quite high -- not having one may cost you the job opportunity. On the other hand, a suit is a depreciating asset. It is also not an income-generating asset (i.e. you may sell the suit the day after the interview at no loss of income.)
Using the reasoning of "debt for appreciating/income generating purchase" will preclude you from buying this suit, sensible though the purchase is.
Here's a simple example to illustrate: you have an interview tomorrow, and you want to buy a suit to be sure you are appropriately dressed for it. The net-present-utility of the suit is quite high -- not having one may cost you the job opportunity. On the other hand, a suit is a depreciating asset. It is also not an income-generating asset (i.e. you may sell the suit the day after the interview at no loss of income.)
Using the reasoning of "debt for appreciating/income generating purchase" will preclude you from buying this suit, sensible though the purchase is.
PS: in an ideal world, you'd rent the suit, or any asset that has only temporary utility and pay depreciation+premium. http://john-joseph-horton.com/papers/sharing.pdf