But if the private banks already have some money they can lend it again to borrowers. So they could be inflating money supply pretty much indefinitely. Sure, the number of private borrowers is limited but they are happy to sign all of their future life earnings away in exchange for some money now. And as supply of money grows inflation happens so borrowers need more and more money feeding creation of more money and further inflation.
The role of central bank as a limiter of credit action (through fractional reserve) is way more important than feeding new core money into the private banking system so it can be borrowed by private borrowers. Feeding new money is kinda optional and it's most important role is possibly enabling new banks to be created. In absence of it only companies that already have a lot of money could create a bank.
The other thing is that if economy development outpaces growth of money supply created by private banks whole system could get stuck in deflation. Which was not great last time it happened.
The role of central bank as a limiter of credit action (through fractional reserve) is way more important than feeding new core money into the private banking system so it can be borrowed by private borrowers. Feeding new money is kinda optional and it's most important role is possibly enabling new banks to be created. In absence of it only companies that already have a lot of money could create a bank.
The other thing is that if economy development outpaces growth of money supply created by private banks whole system could get stuck in deflation. Which was not great last time it happened.