the mythology of Seth Jones

One question. Why, when people talk about Afghanistan being the "graveyard of empires" do they always cite Alexander (who, in fact, conquered exactly as much of what is now Afghanistan as he set out to) and the British (who occupied Afghanistan several times, marched pretty much where they wanted, but decided in the end it was easier to pay off Afghan warlords to run the place for them) and always conveniently "forget" the Arabs (like the Ummayads), the Persians (like the Saffarids, the Samanids, and the Ghurids), the Turks (like the Ghaznavids), Chinggis Khan and the Mongols, Timur and his descendent Babur and the Moghuls, all of whom pretty much rolled over Afghanistan and made it part of their empires? Perhaps because those who do so are predetermined that they want to believe that controlling this important and challenging country is impossible and need a narrative to support that view? *grumble*