I agree in theory but unfortunately I think we need both. I have little confidence in either on it's own. And I've been burned too much by vendor lock-in in the past to ever advocate for ANY service that isn't federated (I use many non-federated services but out of necessity, I would never sell others on them).
I should add that successful & popular federated online messaging services are something we've had since the 1960s so I have yet to see any compelling reason to be perpetuating the walled-garden approach beyond a preference for a totalitarian approach to ecosystem control.