The article doesn't really have enough examples or analysis to justify its categorization of network effects. It deserves a more clickbaity title like "6 runaway startups you won't see coming".
Yup, it just seems like some random unsubstantiated theory being touted by VCs who want to show they're smart.
It's impossible that everyone out there blogging actually knows what they're talking about, and figuring out which ones do is getting to be a lot of work.