They had no need to ferment it or disguise its bitter taste either. A 1:10 dry plant tincture is so potent it is used by the drop to slow heart rate and lower BP in someone with a bounding pulse and high fever. Only someone with a lot of experience would even think of using it.
You’re right. The entire Hellebore Genus is toxic, and although I have multiple advanced degrees in Marketing, Business and Horticulture, I know for sure that I’m not smart enough to mess with that stuff.