The Profit and Interest Gap (the PIG)
When a loan is created, only the principal is created, not the interest. Money to pay the interest must be taken from money already circulating in the marketplace.
Likewise, when a good or service is produced, only the producer's costs are paid out to the marketplace. Money to pay the profit must be taken from money already circulating in the marketplace.
If all sellers are demanding more money from the marketplace than they are contributing to it, new debt is essential (if all goods and services are to be sold).