I am an entity that has an understanding of capitalism that is 3 planes above the average homo sapiens.
Ok, let's be serious. Capitalism requires endless nominal growth (not real growth) because of the way our currency and debt system works. When there is a shortage of money, people start hoarding it, therefore the money supply must keep growing to meet hoarding demand otherwise people stop using money as a medium of exchange. Fiat is issued via debt. To maintain money supply growth the amount of debt in the system must grow. Thus we get endless debt growth. The easiest solution to deal with this is to just let the population grow forever as young people take on debt voluntarily or they purchase products and the companies take debt instead. If you have a nominally shrinking economy either because of a lack of population growth or a recession then the process has been interrupted. Private money creation via debt cannot keep up with the necessary increase in the money supply. It follows that the government has to take the debt on instead. The government must borrow money and do fiscal stimulus until 2% inflation has been reached at which point the economy is growing nominally again. This does not require real growth. We can go one step further and allow public money creation tied to inflation. 0% debt forever with no monthly payments. At this point debt doesn't matter anymore and we can kick the can down forever without real growth. Technically it isn't even debt at this point, it is just an account with a negative balance that tracks how much public money has been issued.