There have been things like this for a fairly long while on Reddit. Mostly, they have been along the lines of organizing a study group version of self-study fol

There have been things like this for a fairly long while on Reddit. Mostly, they have been along the lines of organizing a study group version of self-study following, doing something like a course on OCW. They predated Coursera, and the first three pre-Coursera/Udacity courses for ML, DB, AI got a lot of buzz in that community. However, in general, the problem has had less to do with the need to moderate, and more with the slow decline in enthusiasm when there is insufficient follow through. Perhaps one of the ones that has been the most successful, "carlhprogramming", benefited because it wasn't only lead by someone who wanted to learn along with the rest of the class, but filled the role of instructor. If so, that might not auger well for groups of peers learning together. However, I haven't checked any of these out recently, and I could be completely off base about how ambitious this is and how likely it is to really help a lot of people learn new things.