Economic improvement is not a straight line trajectory
It was the typical "opinion piece as news article" that business writing has evolved into during the 24 hour a day news cycle. One day of news that does not follow the market's script exactly and is then extrapolated into the forecast for the year, for the future.
Sure, the news was well below the consensus of economist's estimates, but what should be just as fully investigated is why the economists were so grossly off the mark. One could suggest that they work in a herd mentality. There are many other reasons for the "miss", but one month does not determine a year.
If someone does not expect corporate earning "growth" to slow down, they are ignoring the base off of which prior earnings have been compared to as the economy slowly advances out of the lingering impacts of the severe depression.
The economy has its challenges and rarely does a country's economy or a company's performance move in a predictable straight line up, even if improving. The U.S economy is not Apple.