First, we've had excellent "Ask HN" submissions in the past which tried to discuss private startup-specific problems that a partner or founder was having. These discussions were timely and relevant, and we were only able to have them because the poster felt they could present their issue anonymously.
Second, I don't believe you've thought through the overhead of your suggestion. Does pg hand-approve new accounts, requiring a faxed copy of a driver's license or other state-issued identification? Or do we wait until someone flags an account as "possiblity not a true identify", and, again, burden pg with chasing that person down until they prove they are who they claim, and with dealing with the complaints it will generate?
Regarding your second point - tying into existing identity providers like Facebook would have little overhead beyond the initial implementation. If you wanted to go a step further, you could create an automated phone verification system, like the one Google uses for new accounts. Again, the intent would be to make it harder to comment or upvote anonymously, not impossible.