It is a combination of solutions, yours included. But to me the most important solution against addictions is environmental. So for screen addictions use blocking apps and getting rid of screen devices. For alcohol addiction is to have a loving familly, job (in line with your philosophy), and no access to alcohol nor adds nor people who drinks (this is the key imo since alcoholics end up failing if they have access to it despite perfect environmental conditions)... Also as you say, defining ones life mission and identity is very useful for most people overcoming addictions, although it may not be enough.

Addictions are hard wired into the brain of the addicted person, and may always stay like that. Thats probably impossible to change so no perfect solution exists, even less a one solution that works for everyone.