Senator Charles Sumner proposed that the states had essentially committed suicide, and should be reincorporated as territories and the process of making them into states be started anew, quite possibly with completely different boundaries. That might not be harsher on the people, but is certainly harsher on the institution of government. Amendments to the Constitution, the presidency, and many other issues are determined by the STATES...
Wartime events could also lead to even harsher feelings. Suppose that, soon after the mass murder/massacre at Fort Pillow, some of the perpetrators had been captured in a later battle, tried by court martial, and hanged, including some officers, or even General Forrest. Rebel reprisals against Union officers could follow, and things go down hill from there.
I admit I was always was a believer in the "state suicide theory.". It might not have been good to implement for political reasons but I believe the Southern States ceased to exist the moment they seceded.