yeah, the idea didn't take off until the previous generation of doctors died. it's a fact that often both encourages and discourages me.
even doctors were too stubborn to accept they may have been wrong about something so important, no matter the evidence. however, even those that are so stubborn that they'll take it to the grave will eventually be passed up by a new generation who has known of this idea since before they were born. at worst, this kind of stubbornnes is only likely to stall progress for 2 generations.
still, millions of people died because humans are stubborn.