I can see how free blog hosts, such as Blogger and Wordpress, might feel more comfortable when registering bloggers and commenters to posts do not volunteer their regular offline names when they are not required. If IP address logs and email addresses are obtained by litigating parties, much of the investigation might move to email providers and ISPs (Internet service providers) and to records of computer activity and digital transmissions.
It can make a lot of difference what digital information is personally identifiable, and who has it.