Can’t positively say as to why, Jim….I just don’t know any that use one over a plug. I suspect it is because it requires the user to make two decisions instead of one.
If clubs use the right size shank plugs…damaging the hole should not be an issue. I’ve seen lots of guys plug 177 holes with 22 shank plugs and that can do damage the hole. Using shot up backers is another trouble spot since that will often create torn holes.
Mike