A good way to ward off trolls
How to Turn Off Comments on Facebook Posts – How to Turn Off Comments on Facebook Posts
Social media offers people a way to stay connected, but it often brings out the worst in people’s behavior. There are times when you want to post something, but people don’t have the ability to comment.
While you can't do this on your personal page, you can disable commenting on Facebook group posts if you have the appropriate admin rights. This is a good idea if you want to make a controversial announcement or a news story that would incite trolls.
Group messages can quickly escalate into discussions, especially if the comment is controversial. As a group admin, you can choose to disable comments to avoid annoying people or becoming bait for trolls.