To clarify, the important thing about "reconciliation" is not about reconciling with war criminals, but about reconciling with supporters of war criminals, which are usually a pretty significant portion (sometimes the overwhelming majority) of the civilian population of the region or community that the war criminal is from.

Often, those supporters have been on the receiving end of pretty serious hardships themselves. That doesn't justify supporting war crimes, of course, but if you don't acknowledge those hardships, you create resentment and the seeds of future strife, rather than healing.