Hmm. I am generally a strong supporter of anonymity and pseudonymity. I think we just have to accept that multiple internet folks may come from the same meatspace body. You are right that sockpuppets made for rhetorical purposes are morally questionable, but that's mostly because rhetoric itself is morally questionable.

My preferred approach is to pretend that names, numbers, and reputations don't matter. Judge only the work, and not the name attached to it or how many comments claim to like it. Of course this is difficult, like the rest of rationality; we do tend to fail on these by default, but that part is our own problem.

Sockpuppetry and astroturfing is pretty clearly a problem, and being rational is not a complete defense. I'm going to have to think about this problem more, and maybe make a post.