If you look closely at US history you will notice that there was a marijuana legalization war around the 50s. Farmers knew that Hemp and marijuana had the ability to be a cash crop. But at the time, lobbyists for Big tobacco believed that it would hurt the sales of Tobacco.
I believe on of the reasons the American government wanted to prohibit marijuana was to destroy the hemp industry. This prohibition literally killed that industry despite all of the uses for the plant rather it was bred for a high THC count or not. I think when it is fully legalized again we will see these plants used in a variety of ways.
It was not because of getting high that marijuana became illegal. It was the fears of the timber and lumber industry that made it illegal. The fact that marijuana could get someone high was just the scapegoat. There would of been no other reason. Hemp was being used for so many things at the time, and instead of welcoming another way to make clothing, paper, and everything else. The men with power and money just made it illegal. That was at a time when competition was not welcomed.
Yes, marijuana prohibition initiatives were put in place to remove the threat on the publishing and paper (wood-based) industry exhibited by the budding hemp industry. Hemp grows more rapidly than traditional paper sources and in many cases, is even more durable. However, if hemp were to be legalized in the US, those in the paper or publishing industries would stand to lose. That is why publishing magnate, William Randolph Hearst so adamantly pushed for hemp prohibition.
No, I don't believe that the prohibition of marijuana was enacted for any malicious reason like destroying the hemp industry in America. I believe that at the time, they really believed that the effects of marijuana were much worse than we now understand that they are. I think that it was just banned out of fear.