This line right here is the key from that article.
"
Net neutrality is intended to prevent companies that provide internet service from offering preferential treatment to certain content over their lines. The rules prevent, for instance, AT&T from charging a fee to companies that want to stream high-definition videos to people."
Basically what is being said is that ISPs cannot manage their traffic period. The very definition of QoS is the preference of some traffic over others. This how network traffic has been managed since the 1990s. The reason why it is not working it is because it is asking for that which is not technically possible.
And as far as Netflix is concerned please take a look at this article. It clearly shows that Netflix was partly to blame due to their to push more traffic than the ISPs they were using could carry. It is a great lesson why we need traffic shaping and how Net Neutrality simply does not work in the real world.