> I'm not sure most people are against going after the suppliers
I see the claim made often, it even commonly pops up on HN. The claim is that the War on Drugs is a failure, because any prohibition efforts are doomed. Laws against a substance merely push it into the criminal sector and don't actually disrupt the supply. So the only outcome is that we get more crime and suffering, but the amount of people using the drug doesn't change.
We saw a similarly argument often used when marijuana legalization was being discussed - legalization wouldn't actually impact the number of people who used the drugs, because prohibition laws don't stop people from acquiring a substance. Naturally, the validity of marijuana legalization goes well beyond it's impact on the number of users, but there were many claims that it wouldn't impact the number of users.
Of course, one can make the argument that the War on Drugs is a good thing but that it's implementation has often been wrong (for instance, that there should be more effort made on going after suppliers rather than users). But it's very common to see people claim that any attempts at prohibition are doomed to failure and cause more harm with little to no benefit.
Edit: To give an example, here's a HN discussion where most of the people are in favor of fully legalizing all drugs:
https://news.ycombinator.com/item?id=10424099