I really would like to see answers to the four questions at the end. Though I would hazard a guess that the answers to the first three can be summed up as "it's easier and cheaper to let China do the dirty work." The last question I cant answer as I don't understand boom-bust mining cycles.
Edit to add:
> After all, it turns out tungsten actually isn't hard to find! It's all over the United States. In fact, it's pretty much all over the world.
The Wikipedia Tungsten article states the largest reserves are in China followed by Canada, Russia, Vietnam and Bolivia. This contradicts the articles claim. Just because it's all over does not mean it is easy to dig up and refine. Some clarification is needed. https://en.wikipedia.org/wiki/Tungsten#Production
Edit to add:
> After all, it turns out tungsten actually isn't hard to find! It's all over the United States. In fact, it's pretty much all over the world.
The Wikipedia Tungsten article states the largest reserves are in China followed by Canada, Russia, Vietnam and Bolivia. This contradicts the articles claim. Just because it's all over does not mean it is easy to dig up and refine. Some clarification is needed. https://en.wikipedia.org/wiki/Tungsten#Production