yes I think the courtesy angle is a big one, but I think her following has dwindled a fair bit over the last couple of years. She used her alleged relationship with the fake rock star for quite a while and that kept people guessing, I suppose they were genuinely interested as to who he was, but as time has gone on, and internet sleuthing has become more popular and accessible, readers have been able to come to the conclusion that it was all just a pack of lies. Her recent attempt to bring him back into the story line was abysmal, and no one believed her, so she very quickly dropped it.
Furthermore, her horrendous treatment of David, and the yawn inducing, on/off status of their relationship, just isn't gripping in any way at all, it is totally cringe-worthy, and of course more people are appalled at how she speaks to and about David. Her idea of being a powerful woman, in control of her relationship, amounts to nothing more than being really mean and really rude. Her treatment of many people that have to deal with her on a daily basis, is just not tolerated now, not that it was ever a good thing to yell at a shop assistant, waiter or vet's receptionist, but more so now, it's just seen as unacceptable and portrays her as a nasty, vile person, and lets face it, it's not big or clever and no one really wants to read about that.
Her latest propensity to chase after men she hardly knows, but disclosing details about them that make them traceable, is another unacceptable trait because everyone knows that if she perceives a slight from someone she will waste no time in calling them out in her national column, with little opportunity for redress and to put their side of the story, which she has pretty much done with Andrew Doe, I for one hope that this is the one that will bite her in the butt and put the column out of its misery. There's loads of up and coming writers who could use that space for something far more meaningful than a constant whinge and bitchfest.
eta in fact it's almost parallel to her SATC heroines, yes 20 years ago it was the happening thing (apparently I never watched it, seeing a bunch of neurotic, fashion and sex obsessed woman in their 30's was not my thing) and a lot of people loved it and related to it and wanted to have that lifestyle. the current reboot though is just cringey and embarrassing and I don't blame Kim Cattrell for not wanting to be a part of it, and the viewership feels the same, and are turning off in droves, massive hype, huge letdown and I think (hope) that's the last we'll hear of them.