What BS? Fairy Tail is, like they have said many times (except for Laxus) one happy dango daikazoku. The only official use for the whole S rank is to limit certain lethal missions out of the hands of people who would likely die trying. It certainly doesn't mean that once you are S rank, you are automatically as powerful as the other S rankers. In fact it doesn't even mean you are stronger than all the non-S rank members. It only means you qualify for a few more missions.
It's no fricking military they are living in where the rank means everything.