Doctors have been known to prescribe drugs of all varieties, all of them poisonous. Doctors have performed surgeries on the wrong patients. Doctors have killed many people with wrong advice. Doctors have also done some good as well.
I think it might be wise to focus on the legitimacy of the advice rather than the person or credentials.
"Doctors have also done some good aswell" ......What an understatement
Perhaps Doctor's wouldn't make mistakes if they weren't so overworked and weren't made to work a ridiculous amount of hours.
As far as prescribing drugs is concerned, Doctors do what they feel is in the best interest of their patient's (as they are qualified to do so), btw, even too much water can be toxic, there is a therapeutic window with everything.
Tell me, if you were walking down the road, minding your own business, and some thug walks up to you and stabs you in the chest for fun (it happens all the time, all over the world), would you prefer to be picked up by a taxi driver? OR picked up by an ambulance with para-medics on board who will keep you alive (they may even bring you back to life) and monitor your condition until you arrive at a hospital, on your arrival there will be a crash team ready and waiting for you, would you prefer to be seen by a witch doctor? OR would you prefer to be seen by a trauma specialist?
As you can see, when it comes down to a matter of life and death, being seen by someone with the right credentials is just that, a matter of life and death.
I work in the Labs of a busy hospital performing blood tests, i love it, the hours are long, and yes, mistakes do happen on occasion, we're only HUMAN!