If you guessed, "to discuss things" you are apparently in the minority on some of the groups to which I subscribe. On more than one occasion, group members have been told by the moderators that they need to refrain from continuing various threads for fear that the lurking masses might unsubscribe. Perish the thought! Do these people not have "DELETE" keys on their computers? Can they not simply ignore threads that are of no interest to them? Can they not choose the "digest" or "no email" version of the group and go peruse the topics that interest them later?? Why should the tone of the group be set by the fear of the loss of unknown lurkers with imagined frustrations? In the most recent instance of this travesty, a new group was established and those who held strong opinions on a particular topic were encouraged to join this new group if they wanted to continue to debate in this arena. And this despite the fact that there was NOTHING about the topic orthogonal to the stated mission of the discussion group.
Moral of the story? Don't join a discussion group unless you are interested in DISCUSSING things! (Or at least reading the discussions of others.) Sheesh.