What do you expect? DMD has become more middle of the road so there are only so may sexual activities for D.
The D Only path has dulled the D Sharing path. It is doubtful we will see D go to a swingers club and have sex just for fun, or see her strip, or see her have sex without F being present (I don't mean NTR), hook up with a girl, or any of a multitude of sexual corruption we thought D would under take back in Chapter 1.
So much promise in the beginning but now it looks like so little variety will become part of D's story.
You have an interesting idea of middle of the road...
Why, given the history of the character over the last 5 years of story development, would Dee what to go to a swingers club and "just have sex for fun"? Do you really see that as part of her character?
Dee had sex with a girl early on, as in her best friend. She hasn't had sex with a girl who is a stranger to her. Once again given the character development why would you expect her to want that?
It's also worth considering whether or not F&D's relationship could survive the level of corruption people discuss here. If the relationship collapses there is no game. You can blame Mr. Dots for not blowing up his game to chase a bunch of tags that reflect the desires of a minority of his followers, but realistically his actions only make sense.
I understand that there is a significant percentage of the people who follow this game who really desire the total debasement of Dee. I also understand that 5 years ago Mr. Dots offered that as a possibility. Didn't happen because she was too cute, too naive, too vulnerable, and weirdly too innocent. She captured the hearts of the patrons and Mr. Dots wasn't and isn't willing to kill his cash cow to cater to the minority who are disappointed.
Lack of variety. She's experienced every type of sex with her father, in a wide variety of places. She's enjoyed lesbian sex with her best friend. Depending on your choices she's screwed her photographer, in a scenario where her father was screwing the photographer's date. She and her father had sex alongside another father daughter couple who were screwing their brains out.She's had a threesome with her father and the woman he plans to make a permanent member of their family. I don't follow the "sharing" path so I don't know if your choice allow her to screw Martin, but I'm given to understand that's available.
She's 18-19 years old. That sexual history seems to offer a lot of variety for someone that age.
Your true complaint is that Mr. Dots failed to choose a story arc that catered to your desired outcome. Fair enough, everyone has preferences and there is no accounting for taste, and in the end the author can only accommodate a limited number of desires.