Ok, so your beef is with marketing teams in movie studios, not with writers and directors. I think that's something completely different than being angry at movies for being unrealistic. You would just like movie posters and trailers to include some info saying "this movie is not historically accurate" and then it would be fine for them do whatever they want?

What specific movies you have problem with? Which movies were marketed as realistic and weren't? I know for example Band of Brothers, Saving Private Ryan, Rome or Deadwood are known for their realism but were they actually marketed as such? No idea. Are we talking about trailers claiming that "this movie is historically realistic"? Interviews with the crew? I honestly never saw any marketing claiming some medieval movie is realistic. If you can show me some examples of movies or shows claiming they are realistic in marketing materials but actually not even trying to be I will 100% agree with you it's unfair and shitty behavior.