Close. Cash has a negative yield once savings exceed investments because any additioan investment in physical capital will produce capital that rats and other vermin nibble on. If the yield is stuck at 0% then the physical capital is gone but the money is still there, leasing to inflation. Since money is a claim on the production of other people, it would be wholly absurd to distort the market by forcing the interest rate to never fall below zero as this does not deal with the rat problem. In fact it makes it worse because holding onto money let's you avoid costs associated to rat damage and therefore it fools our brain into thinking we have something that really isn't there anymore, the rats ate it. So instead, to prevent rats from eating our physical capital, we decided to produce none and leave a portion of the population unemployed. As it is illegal to trade without money the division of labor breaks down, people can no longer feed themselves because it is illegal for them to do so. The masses get angry at the rich because they took all the remaining opportunities while simultaneously pretending to be the heroes with their philanthropy.