By itself, the block is useful, however, when managing very large courses and wanting to "hurry up" participants who have yet to complete the course, you should be able to select all those participants and send them an email, or schedule weekly (or whatever) prompts to get a move on.

You can currently only select everyone or individuals, then send a message. You can sort the report to show participants that have not completed at the top, but with 200+ participants, it is difficult to manage.