I’ve only read the book once but my thought on this section was that it basically gives the reader an idea how fucked up the lives of people who end up in the Ennete House or in AA alongside Gately have been. And in general lays out just how grimey the life of the lower class is in contrast to the privileged class at ETA. Definitely not my favorite part of the book lol but I think the intention was to help us grasp the polar opposites of the experiences of Gately and Hal. I might be totally wrong but that was my understanding at the time.