Because they are not building nations, but hotels for transnational progressives
That is the explanation of why Assad is supposedly a very very bad man. Because he refused to let a bunch of people with prior experience in being paid by the international community for dashing around the world raising female self esteem, stopping the oceans from rising, and caring deeply about the plight of international refugees, from taking power in Syria. And as a result the state department found itself funding and arming a bunch of genocidal totalitarians that make the Taliban and Islamic state look moderate.
They want to turn Afghanistan into a multicultural society where women get massive affirmative action.
“Nation building” equals nation dismantling. The globalist idea of nation is a hotel. Who will fight for a hotel?
If you actually want to build a nation in Afghanistan, so that the holier than thou mullahs will not have power, you start by finding the true king. The true King will of course have policies that are agreeable to the majority of Afghan fighting men. For example he will be opposed to educating girls past puberty, and will want them given education that focuses on their role of wife and mother. The true King will also tend to have policies that are agreeable to the leadership of fighting men, such as low taxes, and policies that are in accord with Afghan tradition, such as mandatory Islam and the execution of apostates.
The problem is that the international community is not building nations, but transnations, which have no natural support among local fighting men.
Progs simply assume they are entitled to rule, the arc of history and all that, and any opposition to them ruling is illegitimate, but they are in fact weak, due to gays and women and all that.
It would be easy to defeat the Taliban and set up a colonial regime in Afghanistan: Kill their leaders, take their women, and convert them to Christianity. It would be even easier to set up a traditional Afghan regime: Find the true King. But a tranzi regime will always need outside military support from unenthusiastic foreign soldiers who resent transnationalism.
The progs want empire, and they want the opposite of empire. They want white males to conquer their empire and hold it in brutal subjection, and they want an empire that hates and punishes white males. The state department cannot make up its mind whether it hates the Taliban the most, or US soldiers the most. It is endlessly puzzled that the Taliban continues to hate progs. Don’t they know that Islam is the religion of peace?
A genuinely independent Afghanistan is not going to be governed by people who want to emancipate women and stop the oceans from rising. So rule it or don’t rule it.
The US government needs to rule Afghanistan or not rule Afghanistan. And if it does not rule, whoever does rule Afghanistan is not going to emancipate women, and if it does rule, is going to have to keep soldiers there indefinitely and let those soldiers get their dicks wet.