In short, they were denying claims willy-nilly to keep their profit margin up.
The sad part is that John Grisham wrote a book about this very topic many years ago.
Something else to think about, from McKinsey & Company, “Accounting for the Cost of Health Care in the United States” (January 2007):
The U.S. spent $412 per capita on health care administration and insurance in 2003 —nearly 6 times as much as other developed countries.
Think our For-Profit, Publically-Traded insurance companies aren’t bloated and living well at the expense of our physical health?