In a recession, spending from the top 10% of the population slows down, which in turn stops the trickle down economics, and hits the lower 90% of the society the hardest. And when that happens after a 2 year long period where they were already hit hard, the effects will be even more long lasting.
[Edit]: Since most of you latched on to the argument that "trickle down economics" doesn't work, I'll clarify. Outside the rhetoric of "Billionaires are hoarding all the money", in a healthy economy, trickle down economics is how most of the businesses work. Every time a person earning six figures goes out buys that extra pair of shoes or goes on that extra vacation or orders in food because they were feeling lazy, it's trickle down economics. It works. When the people with higher purchasing power (I said top 10% for a reason and not top 0.1%) feel the pinch, it has a disproportionate impact on people with less money to spare.