They only "proved" it couldn't break the skin. They didn't prove it was harmless... if one slams into your head, you're going to be on the ground.
Often the injury concerns come not from propeller blade cuts, but a lithium battery getting dropped on someone's head from 200ft when it loses charge unexpectedly.
I have a $50 UDI U818A and (with the plastic frame) if I cut the power, it falls no faster than a leaf. It actually does the same 'wobble' and lands softly on the ground.
Larger multicopters, like the DJI ones in the article, are much heavier. About 5lbs or so. They fall fast and hard.