The Taliban was actually very rapidly pushed out of Afghanistan by the US working together with the Northern Alliance. The real problem was that the US couldn't reach into Pakistan to fully end the Taliban for good. Thus the Taliban was allowed to rebuild and reconstitute its forces over the years waiting for the US to finally pull out of Afghanistan.

But if they had really been a superpower they would have had the diplomatic ties and military strength to do that. I mean Pakistan was harboring Bin Laden himself no less.

However I don't agree, the Taliban was never really eradicated within Afghanistan either. That's why they came back so quickly. In fact even in provinces far from the border they came back every night. Our forces would build a water well for the local citizens, and the same night the Taliban would come and blow it up and rape half the village. They didn't withdraw into Pakistan every night.