Reverse core threaded comment ordering in Drupal 8!
March 2, 2017
The default ordering of all comments in Drupal 8's core comment module is ascending, meaning the oldest comments are displayed first. Sometimes you don't want this.
Assuming your comment field's machine name is field_comments, put this code into a module to get descending comments. I was having trouble with threaded comments, but this works since it alters the query by the c.thread database column instead of just 'torder':