Yeah, but presumably not every ship in Starfleet was close enough to be sent to Vulcan. The universe is, after all, fairly large. So somewhere, there are experienced officers who could have been put in charge. Hell, Spock could have been put in charge. At least he had actual experience. I understand why they didn't do that, but I think it could have been dealt with in better ways than immediately promoting Kirk to captain.
Re: Not a die-hard fan, really, but I've seen most of TOS and read a lot of the novels