Why Joan Didion's Play it as it Lays holds up after 50 years

Joan Didion's (3rd?) novel, Play it as it Lays (1970) was one of the first if not the first to give readers a glimpse of life in SoCal where everyone's in "the business" in the break-out era of the 60s. All of the characters of louche and narcissistic, many are ridiculously wealthy for who knows why as they never seem to be involved in a project w/ any likelihood of success. People speak in cryptic non sequiturs and don't really seem to be listening to anyone but themselves; much time is spent poolside or on the freeways, driving aimlessly. This whole lifestyle was so alien to the NY publishing world, which embraced this and other early Didion works, as to feel like a report from another planet. About 1/3 through this relatively short novel, I find it still reads well and it's still a difficult read: aside from 3 short opening chapters each from one of the characters' POV, JD writes this novel in extremely close 3rd person, focusing on the protagonist, Maria (mar-EYE-uh), a failed actress model of about 30 in the waning days of her marriage to a potentially successful director, Carter. The narration is so close to M's mind that throughout JD introduces names into the story and we really have no idea who they are or why they've entered M's thinking - but this sense of dislocation and confusion is part of the intended mood of the novel, as the characters are so wrapped up in themselves as there's little need to introduce anyone or to give a back story. The essence of the plot up to this point is that M is pregnant and the father is probably not her husband Carter, and C insists that she get an abortion and then "we'll see" about continuing the marriage - part of which involves a battleground of control of their young daughter, Kate, who's in some kind of medical institution under close care - nature of her malady unknown at this point. It's also worth noting that JD's with is rapier-sharp, including many little throwaway lines such as when she introduces a woman who's "very active in the civil-rights movement and group therapy." The novel holds up really well over 50 years, though the world depicted is now much more familiar to us than it was to its first readers, as we've seen sun-drenched, alcohol-soaked milieus in many other books and films since 1970.