All is for naught. It mattered not what ANYONE, Lincoln or anyone else thought at any given time. The fact is that one of the key results of the civil war WAS the end of slavery. And, it is hard to think of the national “differences” leading to civil war were slavery not one of the essential differences. Without slaver the south is not an economy depending on slavery. Without the southern economy depending on slavery a major impediment to unity on many other issues would have been absent, and so would any southern demand for secession in order to keep slavery.
What you say is no doubt true. But something else is just as true: The unconstitutionally all-powerful federal government was also the key result of the civil war. Before the war, states held a constitutionally-supported check and balance against the feds. Not so anymore.