It does not consider a purchase a debt. Purchase is spending to them. Its an exchange of money for goods and services. Debt is something like a loan where you agree to pay it on schedule. Credit cards create a debt, so does a big ticket item like a mortgage or a car loan. You owe the balance until its paid in full.

If for some reason your obligation (debt) is cancelled by the lender the balance owed might be considered income by the IRS.

At least, that is how I understand it.