I mean, you could split up Google into Search, Youtube, and Mail. But in the end, Youtube would still use Analytics and provide Search with all the data they need for their Ad business and Mail would use the Ad tech from Search. With Facebook, it is mostly the same story.
Federated Systems, on the other hand, let you build a distributed network of providers where no provider has all the data in one place, and you can choose which provider you want to trust (or if you want to be provider yourself).