On that note, if one go back to old guy Marx we find that he was no fan of centralization. His thinking was towards workers owning the factory they worked at.

Then again he also apparently had himself talked in circles to make his findings fit the labor theory of value.

Still, while mostly we hear about worker exploitation etc he did dial in on the issue of debt and banking. And how there was a second struggle between industrial capitalists and financial capitalists.

From that an later sources it may well help to think about a economy as a systems of flows. Goods in one direction, and money in the other.

And much like with all asynchronous flow systems, there has to be buffers to even out peaks and slumps.

Banks do that for the money flow via their issuance of debt.