It can be watched here . It was quite interesting. I think the idea, which I also knew, was that such a problem is pretty manageable, however, looking into reports I wouldn't say so. Yeah, I know, one would say that looking in statistics you'll also find that stall/spin is unpreventable/unrecoverable considering the high number of occurences.
LATER EDIT:
Actually the CAR 3 dating from 1949 has that requirement. I think it was a requirement since the first CAR 3 regulations, if I recall corectly dating from 1945. However, I found Aeronca aircrafts are even before that. So, no requirement for them.
It's quite interesting to see that regulations dating from WW2 are very well developed regarding a high factor of safety and in the same type, LSAs certified under years 200x regulations don't have so strict rules. No argue, take it as an amateur observation.