You both have good ideas/reads on what it's like there, but you're leaving out one thing, which is referenced in the OP: Pakistani meddling.
Let's adopt Philly's attitude--I do--that Afghanistan is pretty much f***ed no matter what you do, that it's not even a real country that you can "save." So we go for the least "bad option" and use SM's idea about basically installing and funding a U.S.-friendly dictator who buys off the tribes.
If Pakistan feels that he is simply our puppet or, put more exactly, not enough theirs, they're going to do everything they can to eliminate him/force him out. Of course, Pakistan's interest in meddling in Afghanistan is driven primarily by their conflict with India but there's also probably some intent to keep a buffer between them and the dreaded Shiites from Iran who themselves I'm sure are always meddling in Afghanistan in any way they can.
Just reading that description you start thinking this is less a country and more a sandbox/octagon where, throughout history, various countries have gotten sucked in to fight their little proxy wars against each other. The great irony being we did exactly that in the 80s with the Russians. The other great irony? At that time, with Saudi Arabia and Pakistan as our allies (they provided the money and logistics/staging, respectively, we provided more money and the Stingers), we used the "mujahadeen" as our proxy army to stick it to the Soviets, driving them out.
Flash forward to 2001, where it was now (notice that once we drove out the Russians, we abandoned the place) yes, Pakistan and Saudi Arabia funding and supporting the Taliban, who actually really didn't target us but then did play host to AQ as we all know. Since then, the Taliban has been Pakistan's proxy force to drive US out of Afghanistan but in a bizarre new reality, we keep calling them our "ally" even as they kill our troops and we have to send drones into their country to kill Taliban and Navy SEAL teams to go wack OBL.
Wouldn't this be tantamount to Russia calling Pakistan their ally in the 80s? Because they're doing the same thing to us that they did to the Russians, with our help.
Once you look at it that way you realize how absurd this all is and how, again, Afghanistan seems like nothing more than a McGuffin that only distracts us from who's really attacking us.
The OBL thing should have cemented that idea once and for all.