I mean, you also can't advertise illegal drugs either. Doesn't seem to curb demand though. It may actually be more beneficial to allow these things more broadly, because then social safety features can be wedged in between consumers and suppliers more easily and they don't have to deal with a gigantic shadow market that already gets stigmatised to death by the rest of the population. Just accept that a certain percentage of the populations has screwed up dopamine households and try to keep them away from gangsters as best you can. That would probably help society as a whole more than banning everything and pretending the problem goes away if you close your eyes.

>Doesn't seem to curb demand though.

Because its an addictive product. See also: gambling.