Every time it’s mentioned it’s only about sending e-mail to different providers, but the analogy doesn’t cover for example browsing your e-mail inbox and seeing communication from multiple sources. Just covering how one individual can send messages to multiple individuals via a common protocol is only half the picture.
Honestly it’s more like the old mailing lists (Majordomo days), where individuals would subscribe to a list, but that list might also subscribe to other lists themselves, and then you throw a web interface in front of it.
I’m saddened by the amount of taxpayer money that was spent searching for 5 millionaires who went missing while on a joyride in a test vehicle.