His assumption that people read the whole newspaper just because they paid all of 50 cents or whatever for it is such a huge leap...the whole post is predicated on that being true and it's actually not...
Besides that, he has a point - reading only things that you agree with leads to narrow-mindedness, but it's not something that's new to the Internet era. It's been around for quite some time...ref: religion.
In Brin's 1990 novel "Earth" a character had her news reader (blog reader, twitter client, or whatever else the future calls it) specially configured to include random articles, in order to reduce this sort of bias error.
If I didn't already end up with random other junk on my normal feeds, that would be a really good idea. The major events all somehow make it into my feeds and streams, though... Even here on HN people post a lot of articles that don't fit the site's theme... And many get voted up despite being a complete violation of the rules.
Besides that, he has a point - reading only things that you agree with leads to narrow-mindedness, but it's not something that's new to the Internet era. It's been around for quite some time...ref: religion.