IMO, the whole point of tying multiple email addresses to one Persona account is to prevent websites from figuring out that both addresses are tied to the same

IMO, the whole point of tying multiple email addresses to one Persona account is to prevent websites from figuring out that both addresses are tied to the same person. This is very important when you're trying to build an identity system that you want every website to adopt. Users want to split up their lives into distinct identities (e.g. one for professional settings, one for friends, one for family, one for a secret hobby...). A viable identity system should allow people to manage such identities with ease and switch between them at a moment's notice, without letting anybody else find out that @lubujackson on HN is the same person as @blowjobs on a porn site or a member of an unpopular political movement. Even if somebody carefully compared HN databases with the porn site databases. Having said that, people do change their email addresses a lot more frequently than web devs assume. When this happens, they need to update their profiles in every single website where they used the old address. It would be better if my identity were linked to some sort of key that doesn't change, rather than an email address. Likewise, if there is a proliferation of Persona identity providers, some of them will inevitably go out of business after a while. It should be very easy to migrate one Persona account to another.