Do tell how exactly Arizona is a "fool's gold state"? Trump only won it by 3.5% and he is quite unpopular now.
We also just won four statewide races, including a Senate race. Also, NC is not a "true swing state" considering Mitt Romney carried it in 2012.
It may be more likely to flip than FL, or NC, but those states have more electoral votes.
Romney only won NC by a very small margin. He also won NC by a much smaller margin than AZ.
Even if NC leans slightly to the GOP it is still a swing state. FL may be doubtful because of irregularities and voter suppression, but if the playing field were fair in FL, it would be at least a tossup and maybe even lean D. AZ may be a swing state but it doesn't lean D and may even lean R. It's a question of overall strategy. Do you target big states or small ones?
You can do both, you know. The Dem nominee for President will very likely have north of a billion dollars to play with, which means they can spend a ton throughout the entire battleground.
Also, NC's lean hardly changed between 2012 and 2016 (both years, NC was just under 6 points more GOP than the nation). Meanwhile, Arizona swung from being 13 points more GOP than the nation to a mere 5 points more GOP than the nation.
Who cares if Arizona has less electoral votes than NC/FL, it's more winnable than either and that's what matters.