Doesn't sound convincing. E-mail disproves that. User easily chooses where to register for e-mail service and doesn't find this concept novel at all - e-mail is a well known federated technology which everyone knows these days, not only geeks at all. And, oh horror, the user might need to realize what an e-mail server is in the process of signing up for the service Here it's the same concept but applied to a social network.

Centralized/walled services brainwashing is the way of Whatsapp and other swindlers who exploit simple laziness of registering. It's nothing to do with inability to grasp the decentralization concept by common users.