Eventually he'll realize that this isn't the comics, right?
Well what makes you think the gauntlet can't create matter, we've only seen the complete gauntlet do one thing.
Well we've seen a stone destroy matter on a smaller scale. You could argue that he simply needed all of the stones and the gauntlet to accomplish it on a galactic scale.
Stuff like the power stone to destroy, time stone so it hit everyone at once, mind stone to choose half the population etc.
Shouldn't the reality stone be the one that could create matter on a small scale? We never saw him do that when he had it. So maybe it simply can't.
The gauntlet isn't just a convenient way to hold all the gems at once. Getting the gems together like that gives the user power greater than the sum of its parts.