I completed the CompSci X-Series of MITx on edX, and Software Engineering for IaaS, from BerkeleyX. They were so awesome that I can only think they phased them out because it was such a bargain. Practically, the courses allowed me to change career and to be well positioned.
Well, you're probably at least sortof right. Once the bloom went off the MOOC rose, edX got sold off to an EdTech company. In general, universities decided that shoveling money and effort into the MOOC pit didn't do a lot to further their mission. MIT mostly continues OCW as sort of a sideline. I don't know how many resources actually go into it at this point.