10 Dumbest Things In Star Trek (2009)
1. Captaining Kirk

The role of the ship’s captain confuses a lot of people on Trek and in fandom who don’t all realize that “captain” can mean two things: it’s a rank — like commander or admiral — and it separately refers to the job being the commanding officer on a ship. This is why McCoy could accurately say Commander Spock was the captain in “The Tholian Web,” because Kirk had been declared dead. Spock doesn’t have to hold the rank of captain to be THE captain of the ship.
But that doesn’t mean just anyone can command a ship (emergency situations aside). Being the captain requires knowing everything about how the ship works, and there’s no way even a Brainiac Kirk who can whiz through Starfleet Academy in three years is going to have both the knowledge and practical experience to command a top-of-the-line state-of-the-art starship, no matter that he’s the hero. Starfleet might leave him in provisional command for PR purposes, wait for the public eye to shift, then shuffle him off to a less prestigious command to really earn his stripes.
But the movie is bound and determined to leave Kirk in that chair by the closing credits, no matter how nonsensical that decision is.