There's actually two relevant levels of anonymity online.
1. Alternate persona
2. Complete anonymity
The vast majority of bloggers and forum posters engage in discussions with an alternate persona. This affords them some insulation from real-life consequences and de facto censorship while still having some incentive to cultivate a positive reputation and make meaningful contributions. It's a great balance between freedom to say what you want, and incentive to make it thoughtful.
Unfortunately, for sites that can get tens of thousands of comments per article, where many of those commenters are going to comment just once and never again, alternate personas are really no different from pure anonymity.
1. Alternate persona
2. Complete anonymity
The vast majority of bloggers and forum posters engage in discussions with an alternate persona. This affords them some insulation from real-life consequences and de facto censorship while still having some incentive to cultivate a positive reputation and make meaningful contributions. It's a great balance between freedom to say what you want, and incentive to make it thoughtful.
Unfortunately, for sites that can get tens of thousands of comments per article, where many of those commenters are going to comment just once and never again, alternate personas are really no different from pure anonymity.