Preventing non-friends from commenting on your public posts
First of all, there is the Facebook follow system, which is a great system where anyone can follow you on Facebook without adding you as a friend, so they can see public posts and reach them on their newsfeed. You must activate this system if you want this feature to be effective for you, and everyone can follow you, and you can also follow people back. You can do this by clicking on Privacy Settings, then Followers, and then adding a check mark next to activating Follow, as shown in the image below.
Now, when you write a post on your account and want it to be public – visible to followers, friends, and everyone else – you choose Public while writing the post, as shown in the image below. If you want it to be for friends only, choose Friends Only, and it won’t be visible to followers. You are in full control of the matter.
Now, let’s move to the important part: controlling who can comment on your public posts on your account. You can control this by clicking on Privacy Settings, then Followers, then clicking on Edit next to Followers Comments, then choosing what you want, whether Friends of Friends allowing friends of friends to comment on your public posts, or Friends making comments available only to friends, or Everyone allowing everyone to comment on your posts, so followers can comment on your public posts on your account.
As for the other recurring question about disabling comments completely from friends or everyone? I believe this question is very odd because Facebook is a social network, so if comments are disabled, why post in the first place? Surely, this is not available, and I do not think it will be available in the future. I hope the matter is now clear to everyone, and I hope the explanation is helpful and clear.