Creation of fiat is neccessary because they amount of goods, services, and people are constantly growing. If there was no new fiat, fiat would be deflationary and then nobody would spend it - only hoard it like bitcoins.
hold the phone there Tex.
this sphere is finite. An economy that has to grow to survive is not sustainable.
At that time the creation of fiat can decrease. It's not like it's hardcoded.