I just did a bit of reading on wikipedia about Semmelweis, and I think there is an interesting wrinkle which is normally left out of the Semmelweis tale. The effect size from handwashing was huge, but even Semmelweis couldn't explain why it worked. Handwashing only ended up catching on later once we had the germ theory of disease.

I wonder if a good modern analogy for Semmelweis would be if we did a study on crystal healing or Reiki, and the crystal healing/Reiki was found to vastly outperform placebo pills. (Actually something like this sort of did happen with parapsychology. The effect sizes were pretty small I believe, though.)

Obviously in hindsight, other docs still should've listened to Semmelweis. What I'm trying to get at here is that sussing out the truth can actually be a pretty tricky thing. Even if the docs had somewhat good reason to accuse Semmelweis of spreading medical misinfo, it was still a catastrophic mistake in retrospect.