The truth is that governments take on this job when the liabilities that they built up in order to gain power become greater than their capacity to pay them down, and when there is another country that is trying to pay down it's liabilities by raiding the assets of other nations (e.g. WW1).

There is no necessary role for government in the monetary system, it's a desperate gambit of a failing governance system that starts grabbing control of the monetary system, because that is what their liabilities are denominated in.

If you promise to build a tower 1000 metres tall and you can decide the length of a metre, it's only natural that you will adjust the measuring stick in order to deliver on your promise.