"Why would this thought process be confined to one area?"

It's obviously not, you can find any number of books on Amazon about how the standard of care in virtually every area of medicine is horrifically awful. The one thing these books have in common is that virtually none of them are selling more than 10,000 copies, and of course number of physicians that actually read and take the time to read these books and understand them is only a small fraction of that. The vast majority of doctors can't even name a single recent finding in their own field, let alone the most important ones.