They're called "fudge rings" and as far as I know there is no official reason why they are there.
There are however, lots of opinions and conjecture. :ganz
Hello
I have read elsewhere that according to an older Gibson employee that the “goof rings “ were merely just for decoration. They would do that to the guitars from time to time. Like on some of the 60s or early seventies they would cut and apply those diamond shaped plastic pieces to where the strap buttons are inserted.