Economic theory vs political reality

According to Keynesian economics, yes, a downturn is when you would lower interest rates to stimulate borrowing and investing. And when the downturn has passed, you raise interest rates again so that inflation and moral hazard are kept in check as the economy is supposedly strong enough to go on without that stimulus. But in politics there's never too much of a good thing and fiscal stimulus becomes policy in the good years too. GDP gets a boost, employment numbers get a boost, and every politician from DC to Hawaii can pat themselves on the back for all the numbers while hoping that the negative effects get kicked like a can down the road. Once enough bad investments have accumulated to the point they can't be swept under the rug, investment bubbles burst and the policy of raising interest rates is employed only as a last resort to stifle bad investments on the quick and dirty (again, instead of making those higher interest rates part of the status quo during the good years).