Do any of you know how to make a squadoo or empower network or tumbler style website?

Big question. Do any of you know how to make a squadoo or empower network or tumbler style website? A Membership site anyone can post blog posts to but cant have full access to all my backend admin but they get there own backend user pannel and username password

Not get on their websites but how did they build those kinds of websites?

It's like this squadoo.com/joemallon/blogpost name

Or tumbler.com/wolfdna/blog post name

Crazy question but I have a crazy vision in my head