We cannot live in an idealized world, and the question you ask is a silly question a liberal would ask. Implicit in "Leave Afghanistan Now," (for example) is a pretense that the world would simply return to the status quo ante. But of course, it would not. We are in Afghanistan, so now we must compare what's likely to happen with our leaving with what's likely to happen if we stay.
The question asked by actual adults is: "Do you believe the effects of legalizing some or all of these drugs would involve trade-offs more or less beneficial than the current strategy?" We can debate that question. But we cannot debate a question that compares a fantasy world to the real one.
Of course the issue is whether “the effects of legalizing some or all of these drugs would involve trade-offs more or less beneficial than the current strategy?” I did not want to put words into another poster's mouth, or in this case mouse.
I agree totally with the question above. My original post addressed my opinion that those in favor of legalization misjudge the benefits of that idea while dismissing the downside.