Yeahhhhh, given that the platform here is an install of an open-source CMS, which is presumably managed by a site admin, I personally wouldn't compare them to Twitter in the first place. WP straight-up describes the service as hosting in the letter cutting them off.

But what does get problematic is when your service is an auth provider for numerous others, and a major communication hub in itself, and it becomes possible for you to just suddenly get locked out half your life all in one fell swoop.

WP mostly sidesteps this issue, being an open source project that you're free to just host an instance of yourself. But consider Facebook, with a chat service that's more than a decade old and that covers a quarter of the planet -- and the reaction you would have if an equivalent platform were to lock you out of emails spanning that kind of time frame. Particularly given that it's a closed protocol, and as such any ability you do have to export that data is really only useful for archiving.