Why would they?
They defeated the infidels.
I know this makes sense to most rationale people that have an IQ above 70. However, you have to look at it like this, as this is something that even after explaining it to people, they still just don't totally comprehend with what you're dealing with:
Imagine that back when you were very young and were learning the basic things in life from your parents and family, that you were told that the color of the grass outside was blue. Everyone you knew told you and agreed with this and you accepted and learned that grass was blue, because why wouldn't it be?
Then at some point later in life you come across someone who looks at you weird, tells you that color is actually green and goes out of their way to try and show you that everyone accepts that color as green, to which you are now confused, but still stick to thinking its blue because thats what your family told you and what you've known since you were small.
You go back to your family and tell them this to which they now reinforce that you are correct and it is blue, and anyone telling you otherwise is working for the devil and must be destroyed. You are now dead set in belief that the grass is blue, and now the people telling you its green (which is literally everyone else) is now completely evil with an intent on deceiving and destroying you.
That is Islam. That is the mentality of those in Afghanistan.
Now couple that mentality with a religion that basically states that your God given responsibility is to spread your religion at all costs, and while doing so, any methods deemed necessary are totally ok with zero repercussions from God, as well as either convert or defeat/kill any that are of another religion, and you can now see the problem.
Going further down that road and building on this, you are now muslim, in the 'new country' of Afghanistan where jobs and opportunity have already been non existent, and are now under regional/tribal control. Your government is now some weird tribal religious zealot fascist state that has been under occupation by people who told you the grass is green for the last 20 years. You now have an actual military and equipment and are not short on blue grassers who are willing to martyr themselves to get back at all of the shit that was done to them over that 20 years. You also have China willing to 'help' you.
What do you do?