Uh, the headline claim is about faces, how does it make sense to then insist that you must leave the background in?
The problem was, that with the ML, they ended up building a ruler classifier, because most of the pictures with skin cancer happened to also have a ruler in them to measure the size.
That way we can see how much of the performance is from magic AI pixie dust, and how much is from basic 19th century statistics.
Every time I read a paper like this, I have this Margaret Mitchell talk [1] in the back of my mind.