Why? because they practice bad science!
http://www.geekwire.com/2014/re-consumer-reports-iphone-bending-pencils/
Their pencil demonstration was bas science and not testing phones at their weakest part is bad science as well. The only part of their video that may be accurate are the bend forces in the middle of the devices.
Did you even read the article? Your conclusion that the phone test was invalidated by the pencil example is contradicted by the author of your link.