When you take a look around this place, medical school can't be all that hard.

I started working in hospitals in 1973, when I was still in high school. The experience over the years has provided exposure to me of hundreds of doctors and thousands of nurses. Like any profession, one can experience the entire spectrum of skill and competency, from world-class to "they should be in jail".
Fortunately my good experiences have far outnumbered the bad, but the negatives tend to be better remembered, much like you would  remember a clerk in a store more clearly than you would a polite one. In my early years as a nurse, I found that surgeons (or at least the majority of those I met) were extremely entitled "because we make money for this place and you don't". In one hospital where I worked, the Medical Records Department had refreshments available to entice them to show up and finish incomplete medical records. The physicians never worried about having their privileges suspended, because they were needed to be on-call.
I recall another physician who had totally illegible handwriting. It was basically a squiggle broken up to imply words. The hospital got denied payment from insurance companies because they could not read his handwriting. One would think the hospital would require him to write legibly but, even though he was an ass, he was an ass that generated a lot of revenue, so he was disinclined to straighten up. In the end, the hospital provided a person to take his dictation and type up his documentation for him to sign.
I found that working with physicians who had privileges, rather than being employees of the hospital, could sometimes be a challenge. They came into the hospital to see the patients on their service, and were gone by lunchtime to their offices to see patients in their private practice. If you needed them to come back to the hospital for anything, they simply wouldn't do it, but were more then willing to provide orders you might need over the telephone. I recall one physician I worked with when I was a staff nurse who, when I would call him at night, was always drunk. Before I called him, I prepared a list of what I needed. I would then call him and go through the list. His response was always "fine" and he would hang up the phone.
I have to admit that I would never want to be a physician. What one has to learn to graduate from medical school is staggering. After that comes a multi-year residency. This is an opportunity for new doctors to not only apply the knowledge from medical school, but to also expand and refine that knowledge. While residency gets better as it progresses, the beginning can be extremely stressful. You could always tell the new residents by the amount of "stuff" in the pockets of their lab coat (stethoscope, flashlight, reflex hammer, numerous reference books, etc.) compared to the senior resident, who only carried a pen in his shirt pocket. Today, with the advances in electronics, the reference books are gone, so the difference in what they carry is a bit less.
Where many young physicians get in trouble is being able to apply their knowledge in a practical and safe way. They have learned the subject material in school, they have passed the exam, but now they have to be able to use it to care for patients.
Enter Rachel. Rachel was a nurse in the Emergency Department at the hospital where I worked at the time and who had been one of my mentors. She was older ("seasoned" is probably the preferred term) who tolerated me because I was there to learn from her and took advantage of her wisdom and experience. Many new residents, on the other hand, thought they knew everything, and did not seek advice from Rachel and others when it would have been extremely prudent to do so.
While most residents caught on and learned the importance of listening and collaborating, the new ones who didn't get it were sometimes an ordeal to tolerate.
The title of this piece is a quote from Rachel when a new crop of residents started in July, and she was exposed to some know-it-alls. I think we have all be exposed to individuals at one time or another who have impressive academic credentials, but it really doesn't matter because they can't think their way out of a paper bag. Another one of my favorite quotes from Rachel: "Those two couldn't diagnose a decapitation."
From my perspective, I am less focused on the letters after someone's name; I really don't care what degrees or certifications they have. To me, the most important thing is that you know their job and do it well. That's how you avoid Rachel's wrath.