No, we're not assuming that it gives you more time to study; we're assuming that it gives you more time to space out the classes that you have to take for the MCAT so that you don't mess up your GPA. There are a lot of pre-meds who manage to mess up their GPA even doing things the traditional way; why would you want to make those first 2 years even harder? Yes, there are the exceptional students who can juggle everything, but everyone thinks they're that person. I also didn't sacrifice my grades for the MCAT that spring; those semesters I counted my prep class as an extra class and so dropped down the number of hours I was taking to accommodate it.
Aside from that, I do agree with your basic premise that taking it after the summer following sophomore year makes some sense, if you're doing it for the right reasons; it's a different way of doing things, maybe not strictly better or worse, though I personally think you wind up making things harder on yourself. What I think people are up in arms about is that the OP is seeing the August MCAT as a way to retake the exam, which as you agree, makes no sense and should not be considered in the process.
