I don't think it's about concentration, but more about the exercise of putting yourself mentally in other people's shoes.

And I don't think the benefits of uninterrupted reading are necessarily becoming 'smarter'. They are more like being better able to understand people different from you, more easily able to change your mind based on new information, etc.

Here's a somewhat better article on the topic:

http://www.psychologytoday.com/blog/the-athletes-way/201401/...