I can see your point in cases where there _is_ a contract or an IP agreement or a TOS. How about less formal teams like open source communities, online courses,

I can see your point in cases where there _is_ a contract or an IP agreement or a TOS. How about less formal teams like open source communities, online courses, clubs, etc.? There is no employers who legally owns the conversations, just an admin who usurped rights to control them. Case in point: many online courses use team chat services like Slack for informal communication and socializing between students, to act as virtual campuses. One wouldn't expect private conversations between students to be moderated by the faculty. :)