QE, in conjunction with the Fed dropping FRR to 0% for 6 years, was a direct response to the financial collapse of 2007-8. Obviously policymakers weren't going

QE, in conjunction with the Fed dropping FRR to 0% for 6 years, was a direct response to the financial collapse of 2007-8. Obviously policymakers weren't going to explicitly say - "wow guys we screwed the pooch on this one, time to lower rates and inject liquidity to help banks (and the business/individuals they lent to) clean up their balance sheets full of mispriced, risky assets and avoid financial catastrophe" - but sometimes you need to read between the lines. There is being (equilibrium) and there is becoming (cycles away from/towards equilibrium). The economy is always becoming, but it is striving towards a pure state of equilibrium where supply and demand in every market are working to equal one another, but never getting there.