One of the problems I recall with such mailing-list-based discussion groups was that participants had an expectation that the discussions would stay in the grou

One of the problems I recall with such mailing-list-based discussion groups was that participants had an expectation that the discussions would stay in the group, and that members wouldn't dump such semi-private conversations (which might have included various controversial takes, etc.) onto the larger web - but in many cases, that did happen, with resulting blowback for individuals whose comments were taken out of context. The expectation of any kind of clearly attributable group discussion on the web remaining private appears to be long-gone. Even with closed, in-house corporate or institutional discussion groups, it's likely everything is logged and recorded for review by management at their whim. It's all depressingly Orwellian these days.