You are 100% right if we assume that people engaging in any form of incestuous acts will be dumb enough to be hinting or openly displaying their incestuous relationship in public. I mean , I'm pretty sure that if there is people engaging in an incestuous relationship in real life, they would keep it secret and in private, away as possible from the public opinion for many social, moral and legal reasons, but getting back at AWAM's story which is fictional (obviously) and since it's mostly an incest story and if any form of incest sexual act is going to happen, (whether is realistically portrayed or not) needs to happen, or else what's the point of following the story at all ? because I don't know about other fan/followers of the story, but I personally don't care about this story if it doesn't have any full incest sex scenes .