As firms saw increased demand for their products, they would seek to expand output to meet that demand. They would invest in new capital and hire more workers, and this would create even more demand in the economy. At first this would look like a virtuous circle, one which could lead to an extended period of economic growth.
The problem is that lowering interest rates for a period can not create out of thin air the resources needed for growth. Firms that tried to employ more labour and buy more capital goods would quickly run into shortages. That would lead to cost increases for them, and also lead them to put prices up themselves.