JLS, QE and Keynesian economics are just fancy names for market manipulation. A favorite of politicians looking to show they improved the economy quickly as they are limited in time due to their term. The politicians do not care what happens afterward during the next term. Although QE wouldn't be labeled Keynesian economics, it does get the nod from that group. Both are highly controversial and debated. The problems with these are they lead to bubbles and at the very least are not sound economic building blocks put upon well built foundations, more like a house of cards construction and leads to rollercoaster movements of the economy.
The history of QE is full of notable failures to accomplish the goals and since economies are complex and difficult to prove exactly what happened where, it is difficult to pinpoint exactly how much good, if any was done. Even the best example from a QE has negative results as well.
"I may not agree with what you say,
but I agree with your right to be wrong."