Email listservs, usnet and discussion boards were first generation e-discourse applications. These applications impose a minimum structure on the process of discourse. They basically organize topics and maintain a threading structure that allows for responses to be tracked.
Beyond this, they do not provide any internal structure that might further facilitate the discourse process in reaching some kind of conclusion.
And, even more importantly, they do not provide any management of the explosion of information that comes from the combined contributions of a huge number of participants.