There was no "science" done to prove that washing hands had effect on mortality, until someone tested that and found that to be the case. So it's not "old science" vs "new science" but rather "no science" vs "science". Lead was used because it was available. Radium was used because it was pretty. Bloodletting was considered helpful strictly because of tradition of bloodletting and because no one done the rigorous testing with valid methodology to check if it actually works, or if it's just a folk belief that it does.

You keep presenting cases where people just didn't know something and didn't care to figure it out, and call it "science" because someone baselessly believed in it. It's irrational. And before you start anew with ignoring my arguments and listing more cases of people not knowing something as a proof that scientific process is harmful, I seriously don't care. I originally commented about traditions being bad reasons for doing anything with the assumption we have some common ground in our understanding of how science work, and trying to convice someone that science does work is a fair bit too tall of a task to engage with. I'm not interested in that, sorry.