...except that now (at least AFAIU) we're backing out of those areas and the Taliban are right back in control. Maybe that military-intervention-as-societal-revenge-plot wasn't so helpful?
Precisely because the war wasn't finished... political pressure led to the military being recalled and this is the outcome. Rebuilding a nation does not just happen in a few months, it takes decades of peace. The biggest problem is the lack of commitment, due in part to a public that has lost touch with what conflict is and the will it takes to fight.