There is a upcoming feature (again, indicated rollout schedule is June) to Microsoft Teams that will allow Team owners to set who can post or reply in specific channels.
https://blogs.technet.microsoft.com/skywriter/2019/06/03/office-365-weekly-digest-2019-22/
You can follow up this in the Microsoft 365 roadmap: https://www.microsoft.com/en-us/microsoft-365/roadmap?filters=&searchterms=51786
This feature seems to be very similar to what you can do to General channel at this moment:
What is different is the reply part – it will be possible to control if team members can reply on that channel as well. I assume the general channel controls will change into this new Moderation functionality from the current one.
Why this is important?
When you have organizational, or large Business Unit/Diviosion, teams having thousands of members it will be possible to control one or more channels messages: thus preventing information overload and/or missing key information due to multiple replies and threads that has been started afterwards.
Currently limiting the General channel hasn’t been the optimal solution since there could be needs to create some organizational news, announcements and other important messages spread into different topics. Also I tend to think that general channel is as name suggests: open to all to any kinds of conversations and information sharing.
With careful use of this upcoming feature organizations can create larger teams and reach out people working primarily in their Hub for Work: Microsoft Teams.
Vesa Nopanen - My Metaverse Day 