Curriculum change and strategies, past and present: why is it taking so long?

For the last 30 years or more the old war songs of medical education (community orientation, active learning, etc.) have been repeatedly ventilated in meeting after meeting, article after article. But of the present 1642 medical schools on the planet, only about 100 members of The Network and a few other have put these principles into practice, more or less. Obstacles and constraints are known. Is it the system, or the leadership, or the university culture, or the accreditation rules, or all of the above that are responsible for this lack of progress? Still, some overcame the obstacles, some removed the constraints. It would be useful to be better informed about HOW it was done. I suggest that Education for Health: Change in Learning & Practice (EfH) should present more articles explaining HOW successful schools managed to DO IT or WHY they were NOT able to DO IT.