There was an assumption by many that if there was a room available for cash you could always get it by using points. From what I heard, even some Disney cast members told people this was true.
Apparently with the large number of people wanting reservations on the Dream, they hit the limit for almost all Dream cruises. People suddenly found themselves with cash reservations they could not convert to points like they did in the past.
A big stir happened on the boards and Disney relented and let people do one last conversion.
There was no moratorium, if you wanted a cruise with point availability you still got it. It was just that the Dream and Alaska cruises had no more point availability, so it appeared to be a moratorium. If you wanted a Med, Mexico or repositioning cruise you were mostly fine.
It will probably happen again.