People cannot cope with even the slightest gray area, so they end up saying and doing ridiculous things. Everything has to be 100% good or 100% bad. The political environment makes this worse: if you concede anything at all, it will simply be used as a weapon against you.
Of course, it took decades to get people to acknowledge that the harms of some drugs were far less than the harm caused by policing them, and that the harms had been wildly exaggerated for political reasons, so it's not really surprising that people will jump to deny any harm in case it gets banned again.
Of course, it took decades to get people to acknowledge that the harms of some drugs were far less than the harm caused by policing them, and that the harms had been wildly exaggerated for political reasons, so it's not really surprising that people will jump to deny any harm in case it gets banned again.