I admire Duterte's war against drug. But let's get real, he might reduce the drug deals, labs and everything related into it but still Philippines will not be drug free.
Drug addiction can't be wiped out with the threat of violence. Even in countries such as Saudi Arabia and United Arab Emirates, where drug usage can get you a death sentence, you will find large number of people who take drugs. Addiction to hard drugs can be fought only with awareness and medical treatment. And legalization of soft drugs will help vulnerable individuals to stay away from hard drugs.
In this strategy, there are certainly more advantages than disadvantages. But this kind of business you want to control, and even have a state monopoly. Otherwise, the problem can not win.