Since the early 20th century, the use of cannabis for any purpose fell out of favor by both regulators and Western culture at large.
In the United States, a wave of regulations made access to cannabis more difficult starting from the late 1900s, ultimately culminating in the Marihuana Tax Act of 1937, which effectively made cannabis use a federal offense. Meanwhile, prohibition in Canada lasted for 85 years until being lifted by recent developments.
Interestingly, however, this recent period of 20th century opposition is actually just a small speck in the wider 6,000-year timeline of cannabis. After all, the plant has been widely regarded for its therapeutic potential for many millennia by different cultures around the world.