It should be no surprise that you source you use is an organization dedicated to libertarian political thought and economics...
Makes sense to me that they would have an article stating that the reason for the CW was economic.
The truth be told that is partly true but there were many reasons for the Civil War...it's just not quite as simple as one reason.
Professor DiLorenzo did not say that there was one reason for the Civil War. He said that the economic divisions have not been given the attention properly due.