The only advantage of "persona" and sign-in services, e.g. "sign in with Google", is that you only have to remember an email address and one password to access multiple sites.
You're right these services could be used to track the websites a person visits.
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum You cannot attach files in this forum You can download files in this forum