Why the author assumes the way he uses it is the right way to use it? I think that people from totally different fields of work of my own, but whom I happen to

Why the author assumes the way he uses it is the right way to use it? I think that people from totally different fields of work of my own, but whom I happen to know (a.k.a. family and friends) may, sometime, be useful to my career too. People change careers all the time, I may stay on my fiel but change company, or change the industry I act. These times a diverse network may be useful. Quality may come from proximity, but also may come from diversity. I am prefering diversity right now.