Facebook spent years building out News Feed advertising — not simply the display and targeting technology but also the entire back-end apparatus for advertisers, connections with non-Facebook data sources and points-of-sale, relationships with ad buyers, etc. — and then simply plugged Instagram into that infrastructure.
Then in the article this argument leads to a conclusion that the fb pre-work saved years of monetisation effort for Instagram. Is it not the case, though, that it took years for the first player but would take much less for the followers as they already know what a solid way to do it looks like and they have consumers who are conditioned to this way? Other than the relationships with ad-buyers, everything else on the list is not easy as in a day's work but would take much less time for someone to rebuild using the established paradigm.