Bans done wrong can also make the thing being banned even more appealing, increasing harm. Telling teenagers they can’t do something is always in that realm of calling out forbidden fruit.

Even ignoring that bans tend to make things "cool" to young people, bans done wrong tend to simply concentrate roughly the same or close to the same amount of harm.

Sure, less people habitually got drunk and beat their wives/kids during prohibition, but approximately the same harm still happened, it was just concentrated in all the people who had their lives ruined or got killed by the gangsters or the feds.

Part of the problem is sidestepping around the issue of parental accountability. Certain parties see giving the government increased power into the home, as their opportunity for more control over their populations and any dissent in general. Saying it's "for the kids" is a smoke screen for what they are actually trying to do. The laws they often promote, will do little to solve the actual problem, but will do a lot for them to increase censorship and funnel more money into their pockets.