In an average university, there are decent professors successfully teaching students a topic that they know, and have a bunch of years experience in teaching that topic.
But in a MOOC that is not enough - since a single MOOC can scale to almost all the world needs for that subject, there is no need for a thousand professors teaching the same subject, only the best ones. Some things are unavoidably "lost in translation" due to lack of face-time, but a great prof in a MOOC will still be better than the perfectly ok professor at your closest average university.
To do MOOCs the way they should be done, you don't need to "vet the instructor" in the way that teachers or professors are vetted. The quality threshold here is very simple - are you one of top 10 people in the world in your narrow subject area? If not, you don't need to apply.
The great MOOC courses I had were good only because the teachers were far more qualified than any professors teaching the same subject in 500 mile area from me, that is the value-add of MOOCs. The courses would not have been great if they were taught by simply a random good professor from a good university.