Give it some time though. It may not be long before the 'cut and paste cookie monsters' drop in and enlighten us on the "cold hard facts".
Perhaps it is because the 'cold hard facts' all indicate that the defense of the institution of slavery was the primary reason for secession? If one reads the Declaration of the Causes of Secession for the various states it becomes clear. Mississippi, for example, said,
"In the momentous step which our State has taken of dissolving its connection with the government of which we so long formed a part, it is but just that we should declare the prominent reasons which have induced our course.
Our position is thoroughly identified with the institution of slavery-- the greatest material interest of the world. Its labor supplies the product which constitutes by far the largest and most important portions of commerce of the earth. "
Georgia said,
"The people of Georgia having dissolved their political connection with the Government of the United States of America, present to their confederates and the world the causes which have led to the separation. For the last ten years we have had numerous and serious causes of complaint against our non-slave-holding confederate States with reference to the subject of African slavery. "
Texas said,
"Texas abandoned her separate national existence and consented to become one of the Confederated Union to promote her welfare, insure domestic tranquility and secure more substantially the blessings of peace and liberty to her people. She was received into the confederacy with her own constitution, under the guarantee of the federal constitution and the compact of annexation, that she should enjoy these blessings. She was received as a commonwealth holding, maintaining and protecting the institution known as negro slavery-- the servitude of the African to the white race within her limits-- a relation that had existed from the first settlement of her wilderness by the white race, and which her people intended should exist in all future time. "
Alexander Stephens, vice president of the confederacy, said,
"But not to be tedious in enumerating the numerous changes for the better, allow me to allude to one other -- though last, not least. The new constitution has put at rest, forever, all the agitating questions relating to our peculiar institution -- African slavery as it exists amongst us -- the proper status of the negro in our form of civilization. This was the immediate cause of the late rupture and present revolution."
The southern leadership - in it's own words - makes it clear what the most important factor in their decision to enter into rebellion was and that was the institution of slavery.
Because when it comes to war the winners ALWAYS write the histories.
To find out anything but what the winners want you to know, you must dig further than a normal search will take you.