You misunderstood me.
LitRPG is a genre of writing. They're fantasy novels.
What I described is how most AVNs are assembled. Though I can't be sure. I developed all sorts of games for all sorts of platforms for three decades. I've never even thought of creating an AVN but I did examine the scripting language used for most of them. Putting them together is complex even if our desires are not 😆
Most are developed by individuals using their home computers. A single render can take hours and fail at the last minute. The places I worked for had ROOMS full of computers for that, called render farms.
For animations, that takes some skill. Not only do you have to rig the character, but if you mean to animate it, that's a painstaking process. If you're looking for realism you need to include inserts into muscle groups, often called bones, to serve as attachments, much the way your muscles have attachments to actual bones, so that muscles deform with movement that makes sense. If done right, muscles will appear to flex (deform) with movement as our bodies do. VERY FEW AVN creators have either the skills or the time to do this, much less to animate the characters well. This is why motion capture is still used in game animation but that's outside the realm of an indie budget.
Thus muscular women are rendered as if they're wearing plastic body suits. Muscles are fixed, rigid, and look...well...not great. Knees, elbows, wrists, and ankles often look absurd too.
This is why sex scenes are pretty limited in AVNs. Everyone wants more of them for every gal. And no one wants to see a gorgeous gal killed. That's a kink too far. There's one in Episode 2 that frankly bothered me because the list of evil things that young woman covered in tats was supposed to have done didn't make sense. Plus she was hot 😉
In short, while our desires are simple, creating them in computer animation is anything but, alas.