this place is hopeless. op had already very clearly indicated history prior to that masturbation scare yet the retardoid started blaming everything on it stopping.  as for the question in op, i guess it has a lot to do with the general hygienist mindset that was going strong at the time. people had only recently discovered that surgeons washing their hands and instruments cut mortality rates in operations by two or three. you could easily sell any snake oil and and promise the most extravagant benefits to anything provided it was marketed with the vague idea of being "clean". look at it with the hindsight of the covid hysteria. mix that with protestants eager to go on another no-fun-allowed campaign and early feminists sneaking in to demonize male sexuality: you have a deadly combination.
Japan