I think the biggest plague on the story besides the character bloat is that not only has it been schizophrenically set up as an incest story, and since gone on to retcon that idea and insist vehemently that you gave the MC not one, but two hot moms and a college aged sister because you think incest is icky - but that it is also a world which is fundamentally spineless, and a "hugbox" in more than just a literal sense.
We want to suspend disbelief in stories in order to enhance it, and our own experience of it. When you make a world where everybody in it never says no, has no real morals or convictions, or even opinions of any substance, then nothing taking place in that world actually has any tension, conflict, meaning etc.
We are forced to suspend our disbelief that there's not a single adult in the story (besides Millie, and only for like one in game day) who offers up any opposition to the MC essentially running what looks from the outside like some sex cult; living on a private compound funded by his cradle robbing baby mama who also moonlights as the MCs pimp, sugar momma and shadowy businesswoman.
This suspension of disbelief actively ruins all of the taboo elements of the story. It can't really be taboo or salacious if nobody gives a fuck and treats it like its normal.
Harper going from "don't hurt my daughter or I'll chop your balls off" to dribbling the mc's balls behind her daughter's back should be incredibly salacious, but it just isn't because nobody in the world has any real moral convictions and ultimately nobody in the story is going to give a flying fuck. Nat will forgive the MC quickly if she cares at all, Willabelle will let it slide because she's also going to fucking the MC. At a certain point it all just becomes masturbatory, and I'm not talking about the readers at home.
The MC's relationship with Rachael is also absolutely wild. She supposedly had the hots for him while he was underage, and waited around till the day that he was legal when she immediately starts fucking him and literally pimping him out to other women. It's an absolutely insane story that falls flat because in BDs world its not seen as incredibly taboo and downright predatory, its just wholesome business as usual. Not the MCs Moms, Sister, or loving girlfriends seem to call any of this into question. Racheal is a total scumbag and freak but you with how insane the story's world is, you might not even really realize it unless you step back and think about it. They don't even have to hide any of this from anyone, because nobody cares. Not the university, not your family, not that fella in the alley.
There are many more examples of how compelling this story is or could be when you put it in any real context. I don't even think the story is as bad as most people say, it's the world and the characters' vapidness that ruins it.