What are the dissadvantages of always resume option

Disadvantage of "Always resume"? I suppose a learner might want to start over if it's been a while since they first started a course, and that setting would prevent that. (However, if the course has a built-in menu or other programming that allows the learner to easily revisit the content, that wouldn't be an issue anyway.) 

The advantage of "Always resume" is that the user can't "reset" the course. For example, if it allows only three attempts to pass the test, "Always resume" would prevent the learner from getting extra attempts by starting over after they fail the test the second time.