There are several points on which MOOCs are different from regular Universities:
1) Typically, there are no formal requirements to enroll. If I want to take (say) CS 301 in a formal setting, I must have completed the previous courses. In a MOOC, I can try my hand and probably fail, but no one stops me from trying.
2) Many people find the course title interesting and sign-up only to drop a few weeks later, when the material proves above their competence and/or interest.
3) People who try MOOCs, in my opinion and I have no data to prove one way or another, have a job, family and other obligations which limit the amount of time they can put in. If the course is hard, then they fail, not because the course is bad, simply it requires more time than they thought.
For example, I took a MOOC on Mathematics on Philosophy, both being subjects of interest to me. It turned that the mathematics were more diificult than I had expected as well as the philosophy. I concluded the course and learned quite a lot but I did not bother taking the exam, because I knew I would fail. But I did learn quite a lot of interesting things, even if you could count me as a failure regarding the stats on the course.
The point of view of the academics or the promotors of the MOOC might be quite different from the POV of the people taking the course.