Because 'decades' implies more than one period of 10 years. So in effect, the statement you're repeating purports that it will be at least 20 years before we recover from the financial crisis.
My clients at an international investment bank beg to differ. As do the many, many voices in the media/politics/economics etc. Most point to a longer-than-expected recovery period, but nothing quite so dramatic as 20 years. In fact, much if not all of the hullaballoo about how long it'll take to pay off the debt built up by the bail-out of the banks fails to take into account the almost nailed-on likelihood that those banks will pay the money back (as Northern Rock is doing at an encouraging rate).