zlacker

Regarding your first point - you could enable a special Anon mode and have the user jump through hoops to comment anonymously. I believe impulsive upvotes and comments are the primary reason for declining quality and making real identities the default choice would avoid that.

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.