People forget the most important bit. The clapback to Semmelweiss from other doctors was "A doctor's hands are always clean!"

Humans are irrational fucking idiots and we prove it daily. The number of us who are willing to protect our own in-group over things they don't deserve to be protected over is too damn high.

That is far less cool.

Semmelweiss is also partially responsible for the widespread rejection of his findings. He basically called doctors who did not follow his advice murderers which naturally didn't help his popularity. Antagonising someone who you are trying to convince usually just entrenches their opinions further.