As I recall weapons weren't permitted on the platform.

The society didn't decide, the ruling class decided to use drug policy to attack their own citizens.

History shows that prohibition is an abject failure. The fent epidemic is symptomatic of this failed policy.

If they actually cared about the epidemic, addicts would have access to regulated, pharmaceutical grade heroin whilst also having ready access to treatment.

But then we'd have empty prisons and the police would be free to solve real crimes so we can't have that.

There are healthier middle grounds we could explore where e.g. advertisements are banned and individuals could register themselves as being banned from participating in certain addictive vices because they don't consistently have the willpower to quit or don't want to tempt fate trying it (and make it a crime to sell to an individual who has voluntarily banned themselves), but it's hard to argue that The War on Drugs has been in any way just.

I expect in such a society, certain groups (e.g. Mormons) would normalize banning yourself from vices the day you turn 18.

What is just is decided both by an individual and the society they exist in. "It is one's moral obligation to fight injustice" is a pretty common tenent to hold. Injustice can be city laws encouraging anti-homeless spikes. Injustice can also be genocide in a remote country. Those injustices get fought in very different ways. One can be handled by individual vigilanteeism and peacefully petitioning local governance. The other might require global war.

In my personal belief, everyone[0] has the right and moral obligation to fight the injustice they care about at the level they can manage. If that's handing out water at the protest or inventing penicillin, do what you personally can do to improve the world.

[0]the average layperson, obvious exceptions for power/money apply