Economics is funny because its very anti complex math. For the local economics (household even company level) that makes total sense but for anyone doing research or systems modeling for things bigger than a company the total distain for calculus and non-equilibrium systems really prevents any discussion. I think its because if you remove stability most of supply and demand arguments fall apart. Its crazy because stable systems are extremely rare in natural complex systems its weird to apply it to large parts of economics as a given.

But here I'd caution against the idea that banks (not even central) cannot increase money supply because that's not really true. If a Bank is the backer of both sides of loans or engage in fractional reserve banks (i.e all banks), they can effectively increase money supply which in my opinion is equal to printing money. Especially since in the loan case, the loan is not necessarily a guaranteed asset (think cars in a crash). This effect is called the money multiplier effect via fractional reserve banking. https://www.youtube.com/watch?v=93_Va7I7Lgg

The multiplier is more of ceiling to the amplification rather than it actually happening on loans. None of this necessarily bad loans and investment are really important to other parts of economics but none of it is simple and non of it is stable in the traditional sense