Visual sex scenes can be useful for purposes other than porn; you see the characters' expressions, them bonding, etc. But a narrated or text-only description of sexual encounters just seems gratuitous and like the goal is erotica.
I remember in enemy at the gates, there was a sex scene and it was in no way "sexy" but actually a moving moment of companionship between two people stuck in an impossible situation. I do believe sex can be used as a narrative tool ,but often it's just relegated to titillation, which is currently the case in BG3 for sure. It's "i hate you, i hate you, OMG LETS BANG"