You acknowledged that the Confederacy preferred the Articles of Confederation to the US Constitution. The principal difference between the former and the latter is that the Constitution gave more (albeit still limited) power to the Federal government than under the Articles. One doesn’t have to be a neo-Confederate to see that the antebellum South’s preference for the Articles of Confederation makes the claim that the Confederacy was the precursor of 21st century, Obama/Clinton style Democrats absolutely absurd, unless you think that Obama would have supported the Articles of Confederation as a model for the US government.
No, I'm saying Democrats then and now were exactly the same in supporting oppressive Federal powers which benefitted Democrats and opposing any which did not.
In, let's say 1800, the oppressive Federal power benefitting Democrats was its national support for the institution of slavery generally, and especially in its Fugitive Slave requirements.
So Democrats supported that.
Today Democrats support massive Federal powers except when used against their own voters in, for example "sanctuary cities".