It's simple - in theory - a central planning body, who knows what is best for the rest of society, lowers interest rates (to reduce the cost of capital, encourage entrepreneurial actvities, and stimuluate the economy - and therefore jobs - for the average joes and josephines of the world).
So the 'smartest people in the room' cut interest rates, lowering the cost of capital to the lowest in 5000 years...
But a funny thing happens when the world is saturated in debt, leveraged to the max, and liquidified by lenders of last resort... the textbook breaks!
And the real economy "gets nothing"
But do not let that stop them trying it again.