Reconstruction was defeated by white terrorism of the former slave-owning class, it didn't just fail on its own for no reason because the Republicans were stupid or because it's impossible to defeat racism. The former ruling class never had their land seized or their wealth taken or their social networks broken. If the old power structure isn't dismantled and the old ruling class isn't imprisoned they'll just rebuild. That's why Soviet denazification worked and why US denazification and reconstruction both failed.

Also, you must realize the logical conclusion to your argument is that the Confederacy should have been allowed to exist as part of a two state solution? Like, what exactly would be the difference?