That is an option yes. It could reduce the likelihood that addicts end up in a cycle of incarceration and more extreme drug use. However, without a legal supply, I don't believe it would have any effect towards curtailing gang violence or their funding.

Personally, I believe the legal supply should be delivered by the state. With a focus on providing monitored, unadulterated doses of the safest alternative and a program aimed at weaning the user off in a sustainable manner.