I am a recent dental hygiene graduate.  I honestly didn't know quite what I was getting myself into when I applied for school.  I thought I was just going to learn how to scale.  My education went so much deeper and was much more extensive than just scaling.  Part of my job is to deliver the standard of care and to educate the patient.  If dental assistants are allowed to scale then that is lowering the standard of care because they haven't had the extensive education and training myself and classmates have had. 

I don't think a dentist would want us to do a "simple restoration".  What would they say if we just started filling teeth?  I don't think that's the way it's supposed to go.  If I wanted to fill teeth than I would have gone to school to be a dentist.  If assistants want to scale then they should go to school and become a hygienist!  If the dentists want their assistants to scale it seems it would only be to make more money and I wouldn't want to work for someone more interested in making money than delivering the standard of care to our patients!