From an actual email from Mark Zuckerberg on February 28th 2012:
> Integrating their products with ours to improve the service is also a factor. But in reality, we already know these companies’ social mechanics, and we will integrate them over the next 12–24 months anyway. The integration plan involves building their mechanics into our products rather than directly integrating their products, if that makes sense, by a combination of these two things: neutralizing a potential competitor, integrating their products with ours to improve the service.
> One way of looking at this is that what we’re really buying is time. Even if some new competitor springs up buying Instagram, Path, Foursquare, et cetera, now will give us a year or more to integrate their dynamics before anyone can get close to their scale again. Within that time, if we incorporate the social mechanics they are using, those new products won’t get much traction because we will already have their mechanics deployed at scale.
https://www.acquired.fm/episodes/meta