The major licensing restriction in ExpressionEngine is that it cannot be used as the basis of a hosted blogging venture such as Blogger.com or MySpace.com.  If you are intending to offer blogs to the general public this is not allowed under the terms of our licensing, even if you are giving away the blogs for free.

License issues aside, ExpressionEngine does not currently have a management system in place that permits a user to sign up and receive a totally configured weblog.  You’d have to manually set-up each weblog and assign it to a user.  Templates have to be created, member groups have to be assigned, etc.  While ExpressionEngine supports multiple weblogs, a blogging service requires a lot of extra backend functionality in order to permit easy management (or more appropriately, self management), which means ExpressionEngine is not a suitable fit for the task.