Yes, that's right. MC is Marty Sue, it's DPС's own recollection of his college youth.
MC like other protagonists from other adult games is too flat and lacks individuality. But this makes it easier for the player to associate with him and other colorful characters like Quinn, Tommy, Riona, etc. are much better revealed against his background. MC isn't complex enough to overshadow the other characters and he steps back into the shadows, becoming an observer when the brighter characters come into play.
It's a rule of dramaturgy.
Also MC was the center of the game for only the first two seasons, where the arc of MC's formation took place and now it's obvious that the focus will shift. How interesting the other characters will be is the question.
It's not a rule of dramaturgy or a problem about how interesting the other characters can be. It's the way to write female characters in 2023 even in a porn game.
Here's an example: at the Halloween party, Sage, Jill, Bella, Maya and Josy bond and become friends. What do they all have in common? They are friends and/or lovers of MC. Wouldn't it make more sense if they had bonded through MC? Wouldn't it have been more funny and sexy if the drinking game between them had been instigated by MC and he had been the protagonist of the game (after all, he's the only guy in that moment).
Maybe the girls might be looking for a place with less noise and people to chat, and they ask MC for his room, so they all go with him there, and he takes out a bottle of liquor from his minibar and proposes the game. Then they could play a few rounds, where we would get to know the characters better, and MC could tease the girls and be teased by them. Instead of something like that, he's just a casual spectator at the end of the game, because he happens to pass by and see the girls. Wouldn't you have liked more as a player to have a bigger role in that scene, as Main Character? MC is you, it's me, and all of us who play this game. But DPC decided to let all that happen without MC's intervention. The girls, including his love interests, don't even remember MC (i.e. you, the player) while they are together having a good time. I could give other examples.
The problem is, that's the way to write female characters in 2023. They have to do everything without men. They have to talk to each other, but never about men. They have to be empowered and a man can't come in and solve their problems. Maybe some simple ones, like Jill's at the concert, but nothing more. Great. The problem is that in this game, MC is a man, and most of the characters are women. If things happen without MC's intervention because that is not "feminist", MC, Main Character, you, the player, becomes
SC, Secondary Character, and the player gets bored because he sees that the character he controls doesn't really have much to say in the game.
