You can't fight demographics.
QE in an economy with an aging population simply adds ever more debt to an ever smaller working tax base. In GDP per capita terms Japan is growing well. It is only in GDP total that it is struggling.
The same will soon apply to lots of Europe.
If you enter into this phase of an economy's Developemnt with high levels of government and/or personal debt then it's a road to ruin. The trick is to have strong finances with high savings than an aging population can draw down on to finance their retirement and healthcare.
Politicians mistake is to look at total or outright GDP,not HDp per capita. The latter is what makes people feel rich and consume, the former is what gives politicians bragging rights at G7 or G20 love-ins. They are focussed on the wrong measure.