Plagiarism would still be a problem in a world without papers for the sake of papers. Someone I knew abandoned his PhD after plagiarism of his unpublished work-

Plagiarism would still be a problem in a world without papers for the sake of papers. Someone I knew abandoned his PhD after plagiarism of his unpublished work-in-progress rendered his largely-completed thesis effectively useless. He never really found his way after that, and although his suicide had a number of causes, this did not help. Maybe you are thinking that the PhD mill is itself problematic, but there comes a point where saying "if things were different, this would not be a problem" becomes a way to avoid the issue.