When building web 2.0 links do you submit to the same account?

When building links to web 2.0 why would a normal person create a new account to submit each of article. When building Web 2.0 properties is it better to submit to the same account or not.

SE Nuke and Ultimate Demon builds new accounts for each submission. These guys are a big deal in link building. They should know and yet, it doesn't seem natural, although the effects are obvious (anchor text links in articles pointing to your site).

Wouldn't a single blog owner just use articles and wiki sites and put his submissions on the same account. I don't really know how this works. I only see the outcome and the process of these submission tools. I don't understand why we are doing this stuff in a post Panda world.

It also seems to me that a niche blogger would also not have his link in hundreds or thousands of forums. Even if the anchor in the signature is varied. Who the heck could go to that many forums and if you are legit why join if you are only going to leave one post.

Does anyone know where I can find a post/information about this. I need to know the theory so I can understand what I want to apply my efforts to.