Stop digging the head, we found the reason.
Before starting the serious things, a good news : the characters which we are going to talk about should return to living in Avengers 4. Because yes, it is a “detail” of the film that left many spectators wondering : why is Thanos (Josh Brolin) to kill there no Avengers in single combat ? The Titan is ready to annihilate the half of the universe with its snap-destructive, but not to get its hands dirty in face-to-face ? The only super-hero to be killed directly because of the colossus is Vision, because he has one of the Stones of the Infinite on his forehead. We may be the answer to what looks like an oddity of a writer, and she comes to us from the book The Art of Avengers: Infinity War.
“The plan is to gather all the Stones in the Infinity of the, place [Thanos] in the position of a being so powerful that he is at peace, more resolved and more reasonable. He is not necessarily worried about the idea of killing the hero. The moment it picks up all the stones, he can do what he wants when he wants.” explains Ryan Meinerding, Designer and Supervisor of Art. This explains why the Titan does not kill his opponents in a duel : he has simply not the purpose ! Another reason is probably to look outside of the Marvel universe : the dead prior to the snap are highlighted in the story, with Loki and Gamora each having the must to a scene quite poignant. Let’s hope that the Realm of Quantum, the importance of which has been teasée by Kevin Feige in the Avengers 4, which will reset the clock to the hour (and our super-heroes on foot).