well, it had a lot of output! it completely stifled a whole industry of economic activity, for one. thats sort of my point, you might not be able to make a completely 100% unbeatable ban, but you really don't need to in order to effectively stifle certain kinds of activity. like, the harder you make something to do, the fewer people are going to have the energy to do it. arguments like "why bother, you cant make it literally impossible" miss the point that you can make it difficult enough that for most people it may as well be impossible.
The War on Drugs was a matter of method and intensity; the aim was to completely and swiftly eradicate drug abuse rather than move societal incentives.
This could go either way, as far as I know both are possible
wasn't it to discredit political rivals and minorities? like, there really wasn't ever a strong argument against weed (that relied on that stated aim), especially in a post-prohibition America.