Someone didn't read the article. He already DID, he secretly shot Unsane on iPhone, and was happy with results, and mentioned he would be hard pressed to not do again. We'll have to follow Unsane to see how it does.
Just released my third short. This one shot on iPhone 5s. Waiting for festival responses. Another thread asked what the "best" camera for indie films was. I agree with the poster who said - "The one you have." There are dozens of things more important than which camera you use.