Marijuana is directly related to Hearst's legacy about demonizing cannabis. "Yellow Journalism" was coined due to his smear efforts in regards to cannabis. The conspiracy part of that even is he was afraid that paper from hemp would dethrone paper from wood. Hearst was a newspaper magnate and owed a lot of money to woodpulp paper producers, so that theory doesn't really hold up as he would have benefitted from cheaper to make paper. More likely, he was just one of those bible-thumpers that would decry anything mind altering while downing his 10-martini lunch.