19th Century American attitudes about race were far from those currently accepted. When someone points to discrepancies or deficiencies in Lincoln's record about race it's natural that those who respond will bring in the Confederate record on race and the fact that slavery was an important part of Southern life at the time. Then this is taken for an attack on the South.
The things that you cite are to be deplored. They don't fit into the tone that debates should hold to. But they aren't always characteristic of the posters that you have named, and they certainly aren't unique to them. There is plenty of abuse from the other side that you don't mention. You do a disservice by singling out people that you disagree with in a complaint about things that you object to. There is a big difference between indulging in fruitless debates and resorting to insults.
The comments that you mention are more likely to come from casual passers-by who see Civil War thread after Civil War thread and don't see what the fuss is about. The Rockwell/League of the South world is a small one that circulates the same quotes over and over again and seems to be speaking largely to itself. There are a lot of important and obvious things that this group ignores or denies, and no shortage of those who, happening accidentally upon a Rockwell piece for the first time or the umpteeth time, address these omissions in a colorful or offensive fashion.
I think you're right that neither side will be convinced by convinced by anything said here. But it would be a mistake to say that "neither side will change any minds" or that no one is writing in an attempt to persuade. There are many who are uncommitted and still amenable to reason and persuasion. I had an open mind when I first encountered these threads, and made a decision based on the different arguments and the sources they cited. Others may be able to say the same, without endorsing everything that's said by one side or the other. Even if everyone were committed to one side or another, still the effort to found evidence and craft a reasoned reply could be seen as an effort to debate and persuade. While the debate is frustrating and largely fruitless, it has been an interesting and entertaining way to learn more about American history, and that has been of some value.
I see enough spitting on the culture of the North and the leadership of the Union to make me sceptical of the "We just want to be left alone to honor our heroes" argument. Understand that others want to do the same. There is room for honoring both. But "The South Was Right" school goes far beyond honoring the Confederate dead and actively demeans the cause of those who fought on the other side.
As for Mencken, I think he misunderstands the questions behind the Gettysburg Address. Lincoln wasn't talking about the right of self-determination, but about the survival of free, constitutional and democratic republics. The demands that groups made for self-determination would tear apart self-governing societies, and secession would be a warrant for perpetual war and all the anarchy and tyranny that war brings. You can agree or disagree with Lincoln, but simply giving a green light to every movement that demands secession on its own terms at its own will, doesn't prevent the dilemmas Lincoln calls our attention to. Such a policy would be more likely to create and exacerbate them.
The idea that state sovereignty equals the sovereignty of the people of the states equals freedom is another that can be called into question. The idea of minority rights defended by "state's right's" advocates can also be applied against "state's rights." If I am not free because of the abuses of majorities at the federal level, do abuses of majorities at the state level leave me any freer? Similarly, the idea that "the Confederates went into battle free" is also open to debate. It depends on how one defines "Confederates" and "free." Mencken's sentence opens up too many cans of worms to be accepted at face value as true. A committed group of warriors always goes into battle free, but that doesn't tell us much about the society in which they live, and the rights of others in it, including slaves, oppositionists, taxpayers and conscripts.
The idea that state sovereignty equals the sovereignty of the people of the states equals freedom is another that can be called into question. The idea of minority rights defended by "state's right's" advocates can also be applied against "state's rights." If I am not free because of the abuses of majorities at the federal level, do abuses of majorities at the state level leave me any freer? Similarly, the idea that "the Confederates went into battle free" is also open to debate. It depends on how one defines "Confederates" and "free." Mencken's sentence opens up too many cans of worms to be accepted at face value as true.
Great job. Great summary of Mencken's error in oversimplifying the issues and misrepresenting the words of Mr. Lincoln. Anyone who earnestly consults the record--particularly a certain well known fellow named Washington and another one folks might have heard of named Madison--will find that secession does not equal self-determination, least of all in our system. Washington and Madison said so explicitly more than once. I daresay they are qualified to speak on the subject.
If some reader doesn't believe me (and why should you?) please go do a thorough investigation. I am sure WhiskeyPapa has a few quotations handy to point you on your way. Again, great job x. You nailed it.