I quote what Mary mentioned here: https://tracker.moodle.org/browse/MDL-56630?focusedCommentId=434509&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-434509

For students, the course completion block includes a link to a page where they see their progress towards completion. I can't see anywhere else that the page is easily accessible other than from the course completion block, for students.

And Damyon response:
Mary - what you describe is a terrible problem with our navigation in general. How many teachers know they have to add this block in order for students to be able to access that report ? NOTHING should rely on the blocks for navigation.

I must say that this is also causing problems on the mobile app (we don't have a realiable way for knowing if we should show or not the completion link to users since this information is not returned by the WS that checks the navigation options enabled in the course).

I think that if course completion is enabled, properly configured and the user can see the course completion status report we should display a link in the Navigation menu of the course.