Nowadays most people expect positive results when they go to the doctor.

That's not a new idea!

Lewis Thomas ("The Youngest Science") dates net benefit to well past 1900.

Your first link seems to say that Wootton dates it to antiseptic surgery. But that's just one good thing, which needn't balance many bad things. I've heard that the bad doctors did increased in the 19th century. For example, Lewis Thomas says that homeopathy was a reaction to the increase in the harm of 19th century drugs. Your second link seems to say that Wootton isn't talking about net effects, but of doctors doing any good at all. That's a pretty strong claim.