If I were to look at my own life, it's certainly not the distractions of the internet that are keeping me from long, uninterrupted bouts of reading. I would be surprised to learn if the majority of internet usage overlapped with what was previously "serious reading" time. The nature of content that you find flourishing on the internet would seem to indicate it's being consumed a few minutes at a time.
Life intrudes on serious reading much more than the internet ever will. I think a lot of the authors of these pieces decrying the loss of real reading in the modern age (and they pop up all the time) look back at their lives when they were in their 20's and read so much more, and they want to blame the world around them rather than admit that they have just gotten older and lost the free time that came with being young, being single, being without all the responsibilities that come with age and family.