Doctors are at a bad intersection of customer service and science.

On the one hand, doctors need to sound authoritative to 99.9% of all people since they are almost always delivering news the patient doesn't want to hear (exercise, eat less junk, take these pills 3 times equally spaced not 2 with lunch, etc.)

On the other hand, many doctors just aren't that smart. Being a doctor today isn't an automatic sign to me that you are in the top 1% of brainpower. Some of my doctors are, most aren't. In addition, many doctors don't continue to learn over time. If you do that, you eventually become dumb.

Well if you listen to doctors they'll say we apply scientifically proven methods, and some portion of them actually do science. My impression is that doctors like to sound smarter than they often are. Since medicine is more of an art form than anything - most physicians are like artists (albeit highly trained ones). And as with any art you have the whole spectrum of quality.