As someone who thinks the 'war on drugs' is really stupid, I think it's dishonest to compare direct efforts to stop something (no matter how misguided those efforts may be) to a "magic rock". Obviously drug prohibition has stopped someone from acquiring or selling drugs at some point in time who otherwise would have. Of course, that doesn't make it a financially worthwhile or desirable goal.

I for one have been stopped from having chemical fun numerous times because it simply wasn't convenient enough for me.