I think the tide has shifted. Marijuana laws are incredibly lax now and if anything this kind of plays into the “slippery slope” argument they tried to make for decades.
/s
Also, cheap vodkas are cheaper and more accessible to people who abuse alcohol, not mention far far more palatable. And that's exactly what alcoholics tend toward.
Lots of factors play into which drugs people consume, and prohibition plays a role.
In current times, drinking rates among young people are dropping now that they have access to legal marijuana, which is a good thing from a public-health perspective.
This is even more true of the black market. Legalization will reduce these problems, even with no regulations (which is not the case).