Avengers: Infinity War writer Stephen McFeely revealed that they added some catches to Thanos' powers.

McFeely revealed in the commentary for the film that those catches gave our heroes a fighting chance.

As you can imagine, when you have a gauntlet that has nearly unlimited power, and every time you use it you can do what you want... we wanted to create small physical rules that would allow people to hang in a fight with him, so the idea that he had to, you know, close his fist to use a stone was the bare minimum that allowed us to have a fight.

So that every choice they're making, you'll notice in that last minute of fighting, is to keep him from closing his fist. From Peter webbing it to the cape wrapping around it. added director Joe Russo.