People with guns are nothing without support from local people. They'll always lose to other people with guns and support from local people. Because you need to feed, you need safe passages, you need cooperation with local people. If you have strong back up from another country which will supply you with enough goods, you can suppress all local people, but that's can't continue forever.

And yes, as I see that situation, Afghani local people do support Taliban, like it or not. They are Muslim people and they want Muslim country with Sharia law. Forcing democracy on such people does not do any good. You can't quickly change culture. USSR tried to eradicate religion for 80 years and former USSR countries are very religious atm.