Apple introduced the iPhone in 2007, intending a music player, a phone, and an Internet browser in a single device. A year later something interesting happened: Apple cut the price of the phone in half, and introduced the App Store, a place where developers could offer all kinds of software for the phone, leveraging other aspects like geo-location and the accelerometer. iPhone prices didn’t radically go up until 2014, when Apple had an impressive network of developers, apps, and, yes, customers. Facebook also provided access to customers, attracting developers to this model in its early stages. Things like signing on to other services through Facebook, however, made the company powerful for the way it gave members of the social network easy access to other services. In this case, other sites were interested in Facebook because of the size of its network.As we move further into companies that probably couldn’t exist without the cloud – outfits like Uber, which combine social networking, big data analysis, and mobility, all anchored in the cloud – we find platforms that grow strong through customers. But not, as in the old days, because it attracted developers, but because like Facebook sign-on, the growing size offered members additional benefits.So what has changed? Arthur’s prescient essay offers clues.