I think this approach kinda fixes that issue though, no? You can use it the way it is now, and others can be anonymous.
I mean it would be also nice if you could log into multiple accounts and easily switch between them for each vote and comment, but this is also good, IMO.
That’s what PieFed changes though. You can still track how someone votes, but you can’t tie it to a specific profile (without doing some extra analysis and even then you can’t be completely sure).
Or, with my suggestion, you could track how that specific account votes, but it would be easy to obfuscate who exactly it is and (hopefully) impossible to track to the user’s other identities.