Dear
Geralt From Rivia,
Here's the thing. What you say ABSOLUTELY makes sense in regards that the celibacy of other characters is retarded and unrealistic. And sure, you have the logic that even if you end the game with Sage for example(your avatar after all), that it's natural for lets say Zoey to hook up with Jacob. Both are artists, booth have a pussy between their legs and so on.
It's natural and realistic as you say.
BUT, here's the thing. A fuck ton of men, and I presume players of AVNs don't like something that is called: Tainted Meat/Other Men's Trash/So on.
Because after you finish that Sage route, Being a CHICK offers quite the choice of girls to replay the game for.
And there are people that simply don't wanna play said Zoey route because she is tainted meat so to speak.
And if you make the other girls fuck other characters mid or end game, you create a certain dislike for the girls because if they slept with Dawe, Derek, half of the pussy ass DIKs and so on, you know that their standards are quite low. And in turn, you lose respect for said girls.
While I personally don't think like that, it is a thing.
Once you know the meat has been tainted, it simply ain't fresh for the MC.
While we all know as players that the girls are fucking like rabbits(even your Sage has been tickled by Chad's uninterested homo dick), as long as it is not shown in-game, people can bypass it in their heads and move on. Take Sarah and Mel for example, you don't get that kinky and experienced without some practice, I believe half the college fucked them. But as a player, you still enjoy the novelty of it since you don't see it. Because lets say you see them fucking 3-4 guys during the party, and you are #5, MC should than get an option to say: How about you gals wash your teeth, you still got some Lil Dawe's there.
So, what you say makes sense in real life.
But a lot of people play these games to unwind, they don't need reality within them.
And once you see other girls fucking other dudes, quite a few people lose interest in playing their route after finishing their main route.