I'm reading this interesting book on the global history of prohibition that challenges a lot of traditional narratives. [1] One novel thing in the air at the time was the rise of social science and scientific thinking. Before the early 20th century, there wasn't much hard data on how alcohol led to bad health and safety outcomes. Some of this research probably went too far (equating all alcohol to poison). But new awareness of the real dangers (and lack of evidence for many folk remedies of alcohol like warming you up) had a big impact in convincing people and governments to get on the temperance bandwagon.

[1] Smashing the Liquor Machine: A Global History of Prohibition - https://www.amazon.com/Smashing-Liquor-Machine-History-Prohi.... Especially Chapter 14.