“What is the purpose of the economy?”
The purpose of production is consumption.
The point of consumption (retail sale) is the end of the entire economic process.
Once consumption occurs no valid economic agent has the right to charge the consumer additional costs.
Money has many aspects, but its most basic and important one is that it is accounting and thus must abide by the conventions of that discipline.
Monopolies are glaring contradictions in profit making systems.
For-profit finance has (idiotically) been granted a monopoly charter to do this and it exposes the fact of its economically parasitical nature, its illegitimacy as an economic agent and its de-stabilizing monopoly paradigm of Debt and Loan Only.
Monetary Gifting is the ultimate economic tool, ultimate facilitator of commerce, most ecologically aligned economic factor and most intelligent oppositional force to the tyranny of thermo-dynamics.