My thought of a specialist was that the ability to do anything a family practice doctor could do, and then some, was what it meant that they were specialized.
No, that's definitely not the case.
Every physician has a certain baseline knowledge of how to treat really basic diseases. But there is no way that a specialist = family doctor + specialty skills.
For instance, there is no way that an orthopedic surgeon is capable of managing hypothyroidism as well as a family doctor is. There's also no way that an adult cardiologist can treat children as well as a family doctor can. And there's no way that a pediatric endocrinologist is capable of treating adults.
So an emergency medicine doctor, ophthalmologist, or OB/GYN couldn't work in a free clinic?
Sure they can. But they would have to work in
specialty free clinics.
For instance, an ophthalmologist isn't going to hold free neighborhood cholesterol screenings, or free neighborhood prostate cancer screenings. But an ophthalmologist could participate in free glaucoma screenings, etc.
EDIT: I guess my real question is: what can a family practice doctor do that an ER doctor, OB/GYN, or ophthalmologist COULDN'T do?
A family practice doctor can treat children and men (which an OB/gyn can't - OB/gyns receive very little training in how to treat male diseases, like prostate cancer or erectile dysfunction).
A family practice doctor can take care of people for long periods of time, and manage chronic diseases (which an ER doctor usually doesn't do).
A family practice doctor can take care of people below the neck (which ophthalmologists rarely do).
As you said, pretty much everyone specializes....even the "general" practitioners.