The main purpose is definitely to supply the government with currency. Many countries put imo unnecessary restrictions on themselves and do not borrow directly from the central bank which would be simpler and cheaper.
Seignoriage (the practice of the government directly issuing currency to fund its government expenditures) has been around for about 2500 years and predates the invention of the bond market described in this article by roughly 1500 years.
If the Federal Reserve prints reserves (unlocked money) to buy bonds (locked money) and keeps doing this as they mature so that WALCL goes up and to the right, that's money printing.
> No.
Money itself is essentially a hierarchy of IOUs.
In a modern banking system most money is created alongside debt.
Bank lending creates deposits rather than banks simply lending out pre-existing deposits.
Not all money originates through private bank debt. Central banks create base money (currency and bank reserves) and can create reserves when acquiring assets.