Mattermost - Read Only channel
For the moment, when this option "ExperimentalTownSquareIsReadOnly" is set to true, all the Town Square channels of all the teams become read-only.
It will great to set up this option not globally, but at the team level and not only on the "Town Square" channel but on any public channel.
Thank you for nominating the feature! It is now available in Mattermost v5.22.0 in Enterprise Edition E20 (Beta).