Libertarians in charge would mean more drugs

This is only true if it is the case that the first-order effect of legalizing drugs (legality would encourage more people to take them) outweighs second order effects. An example of the second order effects is the fact that the price is higher encourages production and distribution. Or the fact the that illegality allows them to be used as signals of rebellion. Legalizing drugs would potentially put distribution in the hands of more responsible people.And so forth.

As the evidence based altruism people have found, improving the world is a lot harder than it looks.