good or bad writing can play a lot in how a reader/player may or not identify somehow with the MC or at least in some of the scenes he/she has.
There's also the case of AVN using 1st person viewpoint in many scenes in which the MC interact/speak/etc... with other characters, as 1st person view means that the other characters are looking at the screen, and so at you considering you're staring at the screen too, trying to enforce the "MC is you" feeling.
But there's additionally what the MC is , when he/her is wrote (intentionally or not) as a degenerate, a creep, an idiot, a moron etc... unless you're exactly like that yourself
it's basically impossible to feel any connection to such MC and have "the MC is you" effect regardless if the whole AVN is in 1st person viewpoint or if the text constantly mention "you".
There's also the case of AVN using 1st person viewpoint in many scenes in which the MC interact/speak/etc... with other characters, as 1st person view means that the other characters are looking at the screen, and so at you considering you're staring at the screen too, trying to enforce the "MC is you" feeling.
But there's additionally what the MC is , when he/her is wrote (intentionally or not) as a degenerate, a creep, an idiot, a moron etc... unless you're exactly like that yourself