My post is not political. But as there are ex-military folks here, I'll make it tactical.
Here's what I'd be grilling Pentagon sources on if I were still a national security reporter:
The reason no Americans had been killed in Afghanistan for 18 months is the Taliban wanted us out a badly as we wanted to get out. Also, while the Taliban could mount terrorist attacks and plant IEDs, they had no ability to mass forces for attacks on cities because putting any kind of mobile column on the road was an invitation to being incinerated, ala the Highway of Death in Kuwait.
So why wasn't our exit plan simple:
1. Put up a devastating air cover, F-22s, F-35s and every drone we have, and let the Taliban know that any movement on the roads during our relatively short withdrawal phase would lead to instant death. Back that up with a couple early strikes if they tested us.
2. With that air cover in place, quickly and efficiently pull everyone back to the massive compound in Bagram, with teams of SEALS and Delta Force covering the withdrawals on a local basis.
3. Run a day-and-night airlift to get US civilian personnel, and a select and relatively small group of Afghans who really were essential allies out of the country to other bases in the Middle East. This really shouldn't have taken more than 2-4 days by my calculation.
4. Lastly, pull out the SEALS, Delta and maybe a couple battalions of Rangers providing security at Bagram, fly our air cover to regional bases, and announce to the world that we've quit Afghanistan.
I'm no military expert, but why wouldn't a plan built along those lines, perhaps with a few adjustments, have worked to leave Afghanistan?