But once they have set that up (which they have), they can build a feature once and deploy it on every mobile platform supported, iterate and fix things quickly

But once they have set that up (which they have), they can build a feature once and deploy it on every mobile platform supported, iterate and fix things quickly without distribution delays (like 30-50% is on iOS?). It's not for everyone, and I don't like the Facebook iPhone app and I don't take this approach generally, but it works for Facebook because it works for most end-users.