Spoiler: still doesn't make sense I accept the whole technology argument when realistically do we really think that Tony stark could make something better than the dwarves who made mjomlnier, infinite gauntlet and storm breaker? I sure as hell don't. The only reason they got iron man to kill Thanos was just to service the fans and get rid of the character in a way thats epic enough for people not to complain. Realistically he should have died in infinity war whilst everyone else escaped titan after Thanos threw the moon at it. Its lazy writing to be honest and majorly spoiled the ending for me personally.