I think we are saying the same thing here. 'Kentucky' would take on a fame. The term might well have been used by folks who had no connection to Kentucky. However it was looking back with nostalga that the mystic of the Kentucky rifle was born. By the twentieth century it had become the name of any old long and not so long gun.
When we talk of styles today, and we don't want to say Kentucky rifle unless we mean a rifle built in Kentucky, we are (smugly)demonstrating an arcane knowledge. When we say Virginia rifle we show we know there were local varitions of rifle styles. When we say late Virginia we demonstrate we are playing with the big boys now. We know styles changed over time, and we can tell early from late. Its our own version of saying, 'Well that movie screwd up, all the b-17s were Gs when in the real raid they used mostly Es and a few Fs'