Whether it’s Tony Stark’s alcoholism (which was barely hinted at in Iron Man 2), or the incestuous relationship between Scarlet Witch and Quicksilver depicted in the Ultimate universe, the filmmakers who adapt these stories aren’t necessarily beholden to that specific continuity when they bring these icons to the big screen.
Peyton Reed’s remarks during his interview with Yahoo Movies also emphasizes something that has become notable throughout the history of the Marvel Cinematic Universe.
No matter how dark a film like Avengers: Infinity War may get, certain elements of the comics arguably have very little chance of making it to the big screen.