The wizard of Keynesian economics, High Priest Obama, himself made this argument not too long ago in Illinois. Railing against rising income inequality, the President said,
"This growing inequality isn't just morally wrong; it's bad economics... when middle-class families have less to spend, businesses have fewer customers. When wealth concentrates at the very top, it can inflate unstable bubbles that threaten the economy. When the rungs on the ladder of opportunity grow farther apart, it undermines the very essence of this country."
As my former boss John B. Taylor explains, this "middle-out" view holds that "wider income distribution slows economic growth by lowering consumption demand. Saving rates rise and consumption falls if the share of income shifts toward the top, according to middle-out reasoning, because people with higher incomes tend to save more than those with lower incomes." Thus, the key thing that needs to be done is to stop the rich from hoarding cash in gigantic vaults, but get that money out the door and into the hands of middle-class people who care not one whit for tomorrow and will spend spend spend.
The basis of Keynesian economics is (as by the accounting identity for GDP) that growth comes either from investment OR consumption OR government spending. So if you run up consumption, you're getting "growth." More formalized (but no less wacky) Keynesian economics relies on the idea of aggregate demand, sticky wages, and the need to move the animal spirits of the markets when they won't budge (i.e. when the rich sit on their cash in vaults). The key to all of this is increasing consumption - how can you do this? Increased liquidity. Tax "rebates" and one-time "stimulus" injections into the economy.
The entire basis of both monetary and fiscal policies since 2008 in the OECD countries (indeed, in much of the world) has been to soften the blow of a needed recession... and the way to do that is "put money in people's pockets" and have them spend. Consumption has been the explicit target of policies... and now it's coming home to roost, some people are noticing that hey, this isn't really helping. In fact, it's even more unsustainable and leading to high levels of debt that are very sensitive to macroeconomic fluctuations.
So the worry seems to be that the policy did exactly as it was intended to do, but somehow didn't also cure the issues (lack of investment, paralysis in the economy due to government intervention) that it actually engendered.
Sorry, this one grinds my gears too, but I always find it funny when Keynesians get mugged by reality.