that is true, but there are people in this world that you as a physician can't get a long with, which means you can't give them the proper care that you could give to someone else. Always try to work out your problems with your patients, but if you exhaust all options and can't deal with it, for the sake of a malpractice suit we as physicians have the legal option (FP, etc) to inform the patient that we will no longer be there primary care provider and that they must find a new physician. They have a standard set time in which you must still treat them until they find a new physician (30 or 60 days or something like that), after which time you can refuse to see them without getting charged with abandonment. It should never be taken lightly to refuse a service to patients, mostly because you should want to help everyone. But like I said, we are all human and nobody expects you to be able to get along with everyone you come across.
in an emergency setting due to EMTALA (or something with that acronym) you must stabilize the patient prior to transfer...........if you don't follow this you get like a $50,000 fine and the hospital gets fined as well.
So basically as a primary care provider you do have the option to drop a patient for any reason you see fit, in an emergent situation you have to do everything you can to stabilize the patient and treat them.
There a bunch of laws in each state for this sort of situation though, so you need to know where you practice and what they consider appropriate notification and action.