The use case is to provide information to users, for example, release notes, status updates, etc. In order to keep the channel relevant and to avoid clutter, non-admin users have read-only access.

This feature allows a team to create "reference" channels.

1. team admins: create, read, update, delete
2. non-admin users: read-only

This idea is similar to, and currently under review for Enterprise Edition:

https://mattermost.uservoice.com/forums/306457-general/suggestions/12874797-add-write-policy-for-channels-and-private-groups#comments

This idea is related to:

https://mattermost.uservoice.com/forums/306457-general/suggestions/11205615-different-user-roles-to-configure