“Very sad, but, not at all surprising.”
You’re right, it shouldn’t be surprising; we were told the truth about Afghanistan every single day George W. Bush was president. Somehow the truth, and Cindy Sheehan (remember her?), disappeared when we elected an affirmnative-action token to re-direct our attention from the collapse of our standard of living and our culture.
But, having been involved in Vietnam and what is now called Irregular War since the mid 1970s I am NOT. There was a very popular comedy routine called “What the Captain means to say..” that reflected the differences between the line warrior and the REMFs that “ran” the war.
The problem with Afghanistan, and with Irregular War (IW) in general, is the nature of the beast is so different from conventional war that practitioners can not easily cross from one to the other. I wrote many critical reviews (non-concure with this document as written) of proposed doctrine and position papers repeating this. To become proficient in one form or the other takes an entire military career - 25 years.
Unfortunately, traditional forms of warfare are the only things taught in military schools. Why? Because you can teach a series of procedures that, when followed, provide a good chance of victory regardless of where you are fighting. In IW each country (theater) of operations is unique. You have to extensively study the nation and its history to understand what is causing the IW and how to fight it. What works in county “X” is frequently a total failure in an adjoining nation, Nation “x”. A factor that conventional warriors find unfathomable.