I'll have to watch Adam's episode, but I watched a Netflix documentary five years ago (don't recall the name) that presented the argument that it was primarily the (cotton?) industry that lobbied to classify weed as illegal, because they wanted to destroy the hemp industry (and succeeded) as they were producing clothing.
So it sounds like original bad intent (destroy competition) led to it being abused for further bad intent (racism).
I'm going to be honest, the argument that hemp is a generally great material has always seemed weak to me. There are plenty of countries where growing hemp is legal, and it still never seems to get much use.
It historically has had tons of use. It was pretty much the only material used for making rope for centuries in Europe, and was used widely in building construction too. Hemp cultivation was a crucial piece of colonial Virginia’s economy, heavily promoted by the British government, and it was used for clothing, sails, and even fine textiles as far back as the Viking age (eg, https://www.nature.com/articles/srep02686).
I could provide more references but I’m typing with thumbs - they are easy to find, though.
Adam Conove made a whole episode in his show, "Adam ruins everything", about the true reasons why weed is illegal.
Link: https://www.youtube.com/watch?v=sXPOw2unxy0
Spoiler: it's about giving the government of the US a tool to discriminate black people and mexicans.