Most accurately it was a separatist insurgency. A distinct populace had formed over the generations, separated by much more than distance, but by the tremendous differences between living in the colonies and living in Great Britain. The fact that Colonials were perceived as a lower class of citizen, had little say in their governance, and as their grievances grew, their increasing perception that they had no legal recourse to address the same all contributed to the ultimate "revolution."

The King had several opportunities to apply small, reasonable measures to "reconcile" the differences, but he scoffed at the idea. Better to simply "enforce the rule of law." This is the typical perspective of government in these situations.

Regarding "Legitimacy" of government in Afghanistan, both sides of the the contest share the requisite religious legitimacy. GIRoA possess Western-granted "legal legitimacy," but such legitimacy is like an honorary college degree, it looks good on the wall but won't get you a job. No, the aspect of legitimacy that is in question in this, and most all insurgencies, is the simple recognition by the governed of the right of government to govern them. When foreign regime change takes one party out and places another party in, it is damn hard to get to effective political legitimacy across the entire populace from such an illegitimate start point.

We in the west often miss the main point on legitimacy because we apply the wrong definition. We apply the one that supports and validates our actions. That is not the one that rules among the affected populaces in these places where we opt to intervene. Political legitimacy cannot be granted or declared, it must be earned. Our very presence is perhaps the greatest obstacle to getting to stability in Afghanistan. That is is a pill we need to swallow (along with our pride).

The "experts" have been very, very wrong on this.