A society needs some kind of trust in its money to have a controlled supply of currency. If just anyone could create new money, money would lose its value. There needs to be a limited amount of it for the system to work.
1920s, the Weimar Republic learned this the hard way. Germany had tremendous debt following the Versailles Treaty and tried to pay it by printing more and more bills. The value of the bills became so low that people began using them as wallpaper because it was cheaper.