We failed to accomplish any aspect of "the mission" in Vietnam but that is not the case in Afghanistan. We did, in fact, remove al-Queda, kill its leader OBL, and remove The Taliban from power. We gave Afghanistan a possibility to stop them from returning to power but they seem incapable of doing that. This is their fault, not ours, and the only d$A mistake was in staying to give them that possibility. The hurried bugging out is how most wars end because people become more vulnerable as numbers dwindle. At a certain criticle-mass it must be done fast. This might have gone a bit better if 45 hadn't pulled out most of the protectionary forces for a more orderly bug-out.
It's what happens after the transition. The question I never hear asked. Where would Afghanistan be today of the USA had never been there?