The two things are tied inexorably to each other.
The Mexicans cannot stop the killing without stopping the drugs.
There are Billions of dollars going into Mexico from drug sales. I doubt seriously they really want to stop the drugs, and as long as there are rival dealers there will be killing.
Their Police Departments are a joke and their Military isn’t much better.
Says who? The USA stopped the alcohol-related killings of Prohibition exactly by recognizing that we couldn't stop the drug alcohol.