The medium is the message.
As the article implies, the Age of the Internet has led to a communication standard that allows us to express ourselves in ways that would otherwise make for awkward situations. The shift in political discourse is shaped by print, television, radio, and the Internet, and they are all interconnected and are essentially crossing over one another.
The Internet is a medium of seemingly limitless possibilities and connections. There is mainstream and there is "the underground" and there is the underbelly. Before the Internet, all we had were one-way media or two-way communication via telephone, in-person meetings, or handwritten letters.
If there is indeed a shift in civility, I'm sure much of the cause can be tied into the Internet itself.