So there is no such thing as a sacred cow when it comes to science, or medicine? I would dispute that, but there you go - it is just an opinion.
Has there never, in the history of medicine, been a procedure or treatment that turned out to be wrong? Are all doctors infallible gods who never make mistakes, never use the wrong techniques, and never have to change the way they practice medicine?
Not only does medicine advance, (we no longer perform Lobotomies, nor do we blow tobacco smoke up people's bottoms to revive them after drowning), but medicine has been known to be wrong from time to time. There may be quite a lot of friction when getting the new, improved treatment to replace the old. Not always, of course, but a fine example would be the discovery of a bacteria being the main cause of stomach ulcers. Discovered in 1983 (I looked it up) people were still being treated by "reducing stress" and taking antacids up until past 2000, from what I understand. Very slow to change. No one is perfect.
I live in a country where there is a more jaundiced view of medicine: doctors here don't ask for bribes, but handing over cash may suddenly bring about a miraculous change of treatment, with rapidly improving outcomes. Funny that.