Chris from the Identity team at Mozilla posted this in a separate discussion, but it's a point that shouldn't be missed:
"Mozilla Persona is Free and Open Source all the way down, which is great, but not quite good enough. You need to be able to choose your own provider and switch from one (say Mozilla) to another (say Google or your own server) whenever you want. So Mozilla Persona should just be one of many options for your online account."
The author has a common misunderstanding of what Persona is and what it does. Persona is not an account system and it is not "provided" by Mozilla. It is a federated identity protocol that allows you to use your existing identity (e.g., at Google or Yahoo or Facebook) to authenticate to relying parties. The "account" is held by the Identity Provider (assuming the IdP speaks Persona), and the IdP may also speak other federated identity protocols, e.g., OpenID Connect.
Related confusion is in the below statement:
"Why not have your Persona account also handle your subscription list and logs?"
There is no Persona account, unless the author means the user's account at her Identity Provider.
> the BrowserID/Persona thingy that happily continued the trend that makes your identity owned by a third party
Nah. You could happily choose any Identity Provider that implemented the protocol, including a self-hosted one.