And why didn't QE lead to rampant inflation? In the crash, about $4 trillion evaporated. The danger was a deflationary spiral, not an inflationary one. So the Fed injected $4 trillion back into the economy via QE. The result was that we had a bad recession, but not a deflationary collapse. We had the Great Recession, but not Great Depression II. That was actually extremely well done by the Fed.

Of course, the danger always was whether they could unwind in without making a mess. They seem to be doing well so far.