It's no different than email, though? If you sign off all your blog posts with your BBC email address, and you leave BBC and no longer have email access and can

It's no different than email, though? If you sign off all your blog posts with your BBC email address, and you leave BBC and no longer have email access and can no longer log into your blog or wherever else you have grown dependent on that address for, then you are rightly an idiot for putting all these eggs in a basket you don't own. No one says we have to reengineer the email protocol, they just say to have an email address you control.