Why such a focus of substances and no mention of the more common addictions such as video games, porn and social media?
They don't cause the severe dysfunction found in substance abuse. Opioid addiction for example is among the ugliest things in existence. Video games, gambling, social media addictions are all bad but not to the same degree.
One dorm-mate was kicked out of college because he spent ALL of his time playing WoW (World of Warcraft) and failed all of his classes. (Side note: I remember being scared to go near that game from hearing so many similar stories at the time.) I've known many people who remain unemployed and do nothing but play video games.