Hospitals are buying up doctors, and literally running doctors out of communities if they don't want to be employed. In the ACO model, the doctor works for a hospital...and his/her paycheck depends upon toeing the lines drawn by the hospital CEO. A doctor's duty is to a patient. A hospital CEO's duty is fiduciary...to the organization. If you are sick, you cost more. Doctors will be punished...or fired...for using too many 'resources'.
The ACO model destroys the doctor patient relationship and replaces it with an orgainzation-patient relationship. It is an inherent and unethical conflict of interest. But the government figures it is easier to control 5000 hospitals than 500,000 doctors.