@evan I view it simple like that - can I move my mailbox away from GMail?
I can. I might not want to, it wouldn't be worth my time. But still - I can roll out my own server, and there are literately hundreds of very good mail services. And while running email server has been challenging last 15 years, core is still the same.
So yes, actual federation matters and being afraid someone swooping in is pointless at the moment.