- Low interest rates mean it makes no sense to simply keep cash, it's better to invest in something productive. For companies that's new projects/ideas which create jobs, for individuals that might be spending on goods to stimulate the economy or buying a house.
- High interest rates are a considered a way to reduce "risky" investments. But in reality, interest is rent seeking on capital which benefits (1) lenders/banks (2) capital holders. Cheap capital enables more projects with positive ROI (above cost of capital) to be persued. And this is good for society as it drives innovation and allocates capital to innovators instead of locking it under stagnant rent seeking. Lest you worry, this doesn't hurt capital holders, as they can instead proactively invest in companies and make the same or larger returns, but now capital is allocated by merit of the project being invested in instead of by simply who can afford it because it meets some threshold. This unlocks the "long tail" of innovation. This is what is referenced in the article: 1970s Hertz took a risky bet using debt which paid off to record profits.
- Higher interest really means higher long run inflation. If you can just let money sit in a bank, doing nothing directly productive for society, and there is suddenly more of it, prices will adjust accordingly. With low interest rates, money supply will adjust with GDP growth from innovation and prices might even be reduced by higher competition and discovery of efficiencies. As long as innovation (enabled by access to capital) stays on pace with money supply, inflation stays low.
This is of course a very optimistic way of looking at things which doesn't consider the effect of things like wage growth which has all but stopped. One could argue in a non-inflationary environment that might be ok, but this is a larger topic having to do with social mobility goals rather than just the economics.