I'm not sure I entirely agree with this article.
Obviously having a well thought through idea of the "end game" in terms of monetisation / business model is a powerful thing, but given the tendency of start-ups to adapt and pivot, this can overly dominate thinking early on.
The simplest case studies are the ideas whose value is linked to the size of the community / user base. eBay were able to get round this by only charging the community once it was large enough (ie I imagine they already had the monetisation "end game" in mind) - but twitter, facebook? Not so much.