I wonder for how many of us it is because our favorite character on MASH was Dr. Sidney Freedman? And because when we were about 10 years old the "Billfold Syndrome" episode completely blew our minds.
"Here’s the premise: A young medic arrives at the 4077th with amnesia. Psychiatrist Dr. Sidney Freedman is summoned, who (along with Hawkeye and B.J.’s help) hypnotize the young soldier to bring him back to the exact time and place he lost his memory. They recreate the battle complete with sounds and role playing. It’s maybe the most dramatic scene we’ve even written. I won’t spoil the ending should you not have seen it yet."
I am glad that he doesn't reveal the ending. Let's just say that the patient has a really good reason for becoming amnestic.
I'm also glad that the guy who wrote the script thinks that it represents some of his best, most dramatic work, and that it was based on actual psychiatrists' experiences during the Korean War. It would be a bit embarrassing if the screenwriter had said, "Oh, that piece of schlock? We threw that together one afternoon because the network said we owed them another episode for the season. Really awful stuff."