"In effect, northern gradual-abolition laws have gotten the North off the hook, persuading historians who were educated and who taught in the North for more than a century that slavery was a southern problem rather than a national problem. The regional animosity associated with the Civil War also suffused the consciousness of northern historians, heightening their tendency to ignore the fact that slavery was not simply a southern problem in the post-[Revolutionary]-war era." ~ Gary B. Nash, “Race and Revolution,” Cambridge University Press, 1990, p.30. (Emphasis mine).
And that same attitude and perspective continues, in large measure, to this very day. Thus the negative emphasis on the South on many academic blogs. It is the alter-ego of the Lost Cause mentality in the South.