Federation is cool. I care about it because I care about technical details because I'm a nerd and find such things interesting.
But as a user, I don't want to FEEL the federated nature of a social system. I want to open an app and see a single flat namespace of people and not have to know how they connect to the service.
"What's your twitter" is just like "what's your email" to most humans, including nerds, when not actively nerding. Email became winful when the fereratedness became invisible